You do not have permission to edit this page, for the following reasons:

This IP address has been blocked from editing Wikipedia.
This does not affect your ability to read Wikipedia pages.
Most people who see this message have done nothing wrong. Some kinds of blocks restrict editing from specific service providers or telecom companies in response to recent abuse or vandalism, and can sometimes affect other users who are unrelated to that abuse. Review the information below for assistance if you do not believe that you have done anything wrong.

The IP address or range 44.199.0.0/16 has been blocked (disabled) by ‪Blablubbs‬ for the following reason(s):

The IP address that you are currently using has been blocked because it is believed to be a web host provider or colocation provider. To prevent abuse, web hosts and colocation providers may be blocked from editing Wikipedia.
You will not be able to edit Wikipedia using a web host or colocation provider because it hides your IP address, much like a proxy or VPN.
We recommend that you attempt to use another connection to edit. For example, if you use a proxy or VPN to connect to the internet, turn it off when editing Wikipedia. If you edit using a mobile connection, try using a Wi-Fi connection, and vice versa. If you are using a corporate internet connection, switch to a different Wi-Fi network. If you have a Wikipedia account, please log in.
If you do not have any other way to edit Wikipedia, you will need to request an IP block exemption.

How to appeal if you are confident that your connection does not use a colocation provider's IP address:
If you are confident that you are not using a web host, you may appeal this block by adding the following text on your talk page: ((unblock|reason=Caught by a colocation web host block but this host or IP is not a web host. My IP address is _______. Place any further information here. ~~~~)). You must fill in the blank with your IP address for this block to be investigated. Your IP address can be determined here. Alternatively, if you wish to keep your IP address private you can use the unblock ticket request system. There are several reasons you might be editing using the IP address of a web host or colocation provider (such as if you are using VPN software or a business network); please use this method of appeal only if you think your IP address is in fact not a web host or colocation provider.

Administrators: The IP block exemption user right should only be applied to allow users to edit using web host in exceptional circumstances, and requests should usually be directed to the functionaries team via email. If you intend to give the IPBE user right, a CheckUser needs to take a look at the account. This can be requested most easily at SPI Quick Checkuser Requests. Unblocking an IP or IP range with this template is highly discouraged without at least contacting the blocking administrator.

This block will expire on 12:56, 12 May 2024.

Even when blocked, you will usually still be able to edit your user talk page, as well as email administrators and other editors.

For information on how to proceed, please read the FAQ for blocked users and the guideline on block appeals. The guide to appealing blocks may also be helpful.

Other useful links: Blocking policy · Help:I have been blocked
Your IP address is in a range that has been blocked on all Wikimedia Foundation wikis. The block was made by ‪AntiCompositeNumber‬. The reason given is Open proxy/Webhost: Visit the FAQ if you are affected .
- Start of block: 13:55, 18 August 2022
- Expiry of block: 13:55, 18 May 2025
Your current IP address is 44.199.189.47. The blocked range is 44.199.0.0/16. Please include all above details in any queries you make. If you believe you were blocked by mistake, you can find additional information and instructions in the No open proxies global policy. Otherwise, to discuss the block please post a request for review on Meta-Wiki. You could also send an email to the stewards VRT queue at stewards@wikimedia.org including all above details.

You can view and copy the source of this page:

((Use American English|date=March 2022))
((Infobox weapon
| name           = B61
| image          = B-61 bomb.jpg
| image_size     = 300
| caption        = B61 training unit intended for ground crew. It accurately replicates the shape and size of a "live" B61 (together with its safety/arming mechanisms) but contains only inert materials
| origin         =
| type           = [[Nuclear bomb]]
<!-- Type selection -->
| is_explosive   = yes
<!-- Service history -->
| service        =
| used_by        = United States
| wars           =
<!-- Production history -->
|designer        = [[Los Alamos National Laboratory]]
|design_date     = 1963
|manufacturer    = [[Pantex Plant]]
|unit_cost       = $28 million (Mod 12)<ref name="FAS12">((cite web |last=Kristensen |first= Hans |url=https://fas.org/blog/ssp/2012/07/b61-12gold.php |title=B61-12: NNSA's Gold-Plated Nuclear Bomb Project. | access-date = 2012-07-26 |archive-url=https://web.archive.org/web/20130116152834/http://www.fas.org/blog/ssp/2012/07/b61-12gold.php |date=2013-01-16 | archive-date = 16 January 2013 ))</ref> 
|production_date = 1968 (full production)
|number          = 3,155
|variants        = 13
<!-- General specifications -->
|spec_label      =
|weight          = ((convert|715|lb|kg))<ref name=b61history/>
|length          = ((convert|141.6|in|m))<ref name=b61history/>
|part_length     =
|width           =
|height          =
|diameter        = ((convert|13.3|in|cm))<ref name=b61history/>
<!-- Explosive specifications -->
|filling         =
|filling_weight  =
|detonation      =
|yield           = Believed to be either 0.3–340 kt<ref name=NukeArchive>((cite web |url= http://nuclearweaponarchive.org/Usa/Weapons/B61.html |title= The B61 Bomb |publisher= Nuclear weapon archive |date= 9 January 2007 |access-date= 2018-03-28 |archive-url= https://web.archive.org/web/20090227003412/http://nuclearweaponarchive.org/Usa/Weapons/B61.html |archive-date= 27 February 2009 |url-status= live ))</ref> or 0.3–400 kt<ref name=Kristensen2015/> in the weapon's various mods.
))

The '''B61''' [[nuclear bomb]] is the primary [[thermonuclear weapon|thermonuclear]] [[gravity bomb]] in the United States [[Enduring Stockpile]] following the end of the [[Cold War]]. It is a low-to-intermediate yield [[strategic nuclear weapon|strategic]] and [[tactical nuclear weapon]] featuring a two-stage [[radiation implosion]] design.<ref>((cite web | first = Carey | last = Sublette | url = http://nuclearweaponarchive.org/Usa/Weapons/B61.html | title = The B61 Bomb | publisher = Nuclear Weapon Archive | date = 9 January 2007 | access-date = 2012-06-09 | archive-url = https://web.archive.org/web/20090227003412/http://nuclearweaponarchive.org/Usa/Weapons/B61.html | archive-date = 27 February 2009 | url-status = live ))</ref>

The B61 is of the [[variable yield]] ("dial-a-yield" in informal military jargon) design with a yield of 0.3 to 340 kilotons in its various mods ("modifications").<!--=====-----===== this is not a misspelling, stop changing it to "modes" -----=====-----=====-->  It is a Full Fuzing Option (FUFO) <!--=====-----===== this is not a misspelling, stop changing it to "fusing" -----=====-----=====-->weapon, meaning it is equipped with the full range of fuzing and delivery options, including air and ground burst fuzing, and free-fall, retarded free-fall and laydown delivery.<ref name=b61history>((cite report |date=August 1971 |title=History of the TX-61 Bomb |url=https://osf.io/bfjrc/ |publisher=Sandia National Laboratories |number=SC-M-71-0339 |access-date=2021-02-05 |archive-date=2021-03-30 |archive-url=https://web.archive.org/web/20210330090725/https://osf.io/bfjrc/ |url-status=live ))</ref> It has a streamlined casing capable of withstanding supersonic flight and is ((cvt|11|ft|8|in|m)) long, with a diameter of about ((convert|13|in|cm|0)). The basic weight of the B-61 is about ((convert|700|lb|kg|-1)), although the weights of individual weapons may vary depending on version and [[fuze]]/retardation configuration. As of 2020, the weapon was undergoing a 12th modification. According to the [[Federation of American Scientists]] in 2012, the roughly 400 B61-12s will each cost "more than its weight in gold" - $28 million apiece.<ref>((cite web | url=https://thebulletin.org/2024/02/why-the-biden-administrations-new-nuclear-gravity-bomb-is-tragic/?utm_source=Newsletter&utm_medium=Email&utm_campaign=ThursdayNewsletter02152024&utm_content=NuclearRisk_GravityBomb_02132024 | title=Why the Biden administration's new nuclear gravity bomb is tragic | date=13 February 2024 ))</ref><ref name=FAS12/>

==Development==
[[Image:NukesGulf B-61.jpg|thumb|right|A B61 bomb undergoing disassembly.]]
[[File:B61 nuclear bomb.jpg|thumb|B61 bomb casing; [[MAPS Air Museum]], North Canton, Ohio.]]

In 1961 a report was issued indicating Navy and Air Force interest in a lightweight bomb to replace existing weapons, but that both services had considerably different military requirements for such a weapon.((citation needed|date=February 2024)) However, the authors((who?|date=February 2024)) of the report((which?|date=February 2024)) believed that due to advances in technology it was possible for a single weapon to fulfill both requirements. This was followed by a report from Sandia in mid-1962, that believed that a lightweight nuclear bomb with full fuzing option was possible and that such a program could be completed in a short time-span, possibly by 1965 or 1966.<ref name=b61history/>

Development of the weapon that would become the B61 was authorized in December 1962. The justification for the program was that the new weapon would modernize the nuclear arsenal, improve the capability of aircraft and simplify the nuclear weapons inventory by replacing lower-yield versions of the [[B28 nuclear bomb|B28]] and [[B43 nuclear bomb]]s. The desired production date was June 1965.<ref name=b61history/>

The weapon was designated the TX-61 in January 1963. Due to the short time-scales, it was decided to make maximum use of off-the-shelf components such as those developed for the [[B57 nuclear bomb]]. Environmental conditions specified included an indefinite temperature range of ((convert|-60|F|C)) to ((convert|160|F|C)), shocks of up to 40g, and in flight temperatures of up to ((convert|275|F|C)) for up to 40 minutes. Parachute deployment was specified to produce a maximum load of ((convert|255|g-force|m/s2)).<ref name=b61history/>

The weapon was designed and built by the [[Los Alamos National Laboratory]] in [[New Mexico]]. Production engineering began in 1965, with the first war-reserve B61-0 weapon accepted by the AEC in December 1966. However production was halted in May 1967 for design modifications to be made before resuming in January 1968.<ref name=b61history/> Shot [[Operation Flintlock (nuclear test)|Flintlock Halfbeak]] in June 1966 may have been a full yield test of the weapon with other tests conducted between 1963 and 1968 at the Nevada Test Site.<ref name=NukeNotebook/>

During testing, spin motors were added to the weapon to produce a spin of 5 revolutions per second. This was to improve stability and decoupling during high speed delivery. Three alternatives to the weapon were also explored for still-classified reasons. The first alternative was halted due to its similarity to the original TX-61 design, and the Department of Defense was unfavorable to the second option which halted its exploration. The TX-61 design was ordered to "proceed along the lines" of the third alternative in May 1964, though it is unclear what that means.<ref name=b61history/>

Total production of all versions was approximately 3,155, of which approximately 540 remain in active service, 415 in inactive service and 520 are awaiting dismantlement ((as of |2012| lc=on)).<ref>((cite web |url= http://www.ucsusa.org/sites/default/files/legacy/assets/documents/nwgs/B61-life-extension-program-FS.pdf |title= The B61 Life Extension Program |publisher= Union of Concerned Scientists |date= May 2013 |access-date= 8 July 2017 |archive-url= https://web.archive.org/web/20150616040431/http://www.ucsusa.org/sites/default/files/legacy/assets/documents/nwgs/B61-life-extension-program-FS.pdf |archive-date= 16 June 2015 |url-status= live ))</ref>

13 versions of the B61 have been designed, known as Mod 0 through Mod 12.  Of these, nine have entered production. Each shares the same [[physics package]], with different [[Nuclear weapon yield|yield]] options. The newest variant is the Mod 11, deployed in 1997, which is a ground-penetrating [[Nuclear bunker buster|bunker busting]] weapon. The Russian [[Continuity of Government]] facility at [[Kosvinsky Kamen]], finished in early 1996, was designed to resist US earth-penetrating warheads and serves a similar role as the American [[Cheyenne Mountain Complex]].<ref>((cite web | archive-url= https://web.archive.org/web/20130424050959/http://www.windowonheartland.net/2012/02/russias-top-secret-bases.html |title=Window on Heartland: Geopolitical notes on Eastern Europe, the Caucasus and Central Asia | archive-date = April 24, 2013 | url = http://www.windowonheartland.net/2012/02/russias-top-secret-bases.html | date = February 2012))</ref><ref>((Citation | last = Gertz | first = William ‘Bill’ | url = http://www.globalsecurity.org/wmd/library/news/russia/1997/bmd970404a.htm | title = Moscow builds bunkers against nuclear attack | author-link = Bill Gertz | newspaper =[[The Washington Times]] | date = April 1, 1997 | publisher = Global security | access-date = May 12, 2014 | archive-url = https://web.archive.org/web/20140309201007/http://www.globalsecurity.org/wmd/library/news/russia/1997/bmd970404a.htm | archive-date = March 9, 2014 | url-status = live ))</ref>  The timing of the Kosvinsky completion date is regarded as one explanation for U.S. interest in a new nuclear bunker buster and the declaration of the deployment of the Mod 11 in 1997: Kosvinsky is protected by about ((convert|1,000|ft|m)) of [[granite]].<ref>((cite web |url= http://www.globalsecurity.org/wmd/world/russia/kosvinsky.htm |publisher= Global Security |agency= Weapons of mass destruction |title= Kosvinsky Mountain, Kos'vinskiy Kamen', Gora, MT 59°31'00"N 59°04'00"E, Russia |access-date= 2014-05-12 |archive-url= https://web.archive.org/web/20140805043607/http://www.globalsecurity.org/wmd/world/russia/kosvinsky.htm |archive-date= 2014-08-05 |url-status= live ))</ref>

The B61 [[unguided bomb]] should not be confused with the [[MGM-1 Matador]] [[cruise missile]], which was originally developed under the bomber designation B-61.

==Deployment==
[[File:B-61 bomb (DOE).jpg|thumb|B61 bomb components. The physics package is contained in the silver cylinder center-left]]

The B61 has been deployed by a variety of US military aircraft. US aircraft cleared for its use have included the [[B-1 Lancer]], [[B-2 Spirit]], [[B-52 Stratofortress]], [[F/A-18 Hornet]], [[A-6 Intruder]], [[Douglas A-4 Skyhawk|A-4 Skyhawk]], [[General Dynamics F-111 Aardvark|F-111]], [[F-15E Strike Eagle]] and [[General Dynamics F-16 Fighting Falcon|F-16 Fighting Falcon]] and the [[F-35A]]. As part of NATO Nuclear Weapons Sharing, [[German Air Force|German]] and [[Aeronautica Militare|Italian]] [[Panavia Tornado]] aircraft can also carry B61s.<ref name=NukeArchive/> The B61 can fit inside the [[F-22 Raptor]]'s weapons bays and will also be carried by the [[Lockheed Martin F-35 Lightning II]].<ref>Grant, Rebecca. [http://www.airforce-magazine.com/MagazineArchive/Pages/2010/July%202010/0710nato.aspx "Nukes for NATO."] ((Webarchive|url=https://web.archive.org/web/20101207023456/http://www.airforce-magazine.com/MagazineArchive/Pages/2010/July%202010/0710nato.aspx |date=2010-12-07 )) ''[[Air Force Magazine]]'', July 2010</ref>

B61 tactical variants are deployed with NATO allies in Europe as part of the [[Nuclear sharing|NATO Nuclear Weapons Sharing Program]].<ref>"The Bulletin of the Atomic Scientists", 26 October 2013</ref> About 150 bombs are stored at six bases: [[Kleine Brogel Air Base|Kleine Brogel]] in Belgium, [[Büchel Air Base]] in Germany, [[Aviano Air Base|Aviano]] and [[Ghedi Air Base]] in Italy, [[Volkel Air Base]] in the Netherlands and [[Incirlik Air Base|Incirlik]] in Turkey.<ref>((Cite web|url=https://www.demorgen.be/gs-b051dc18|archive-url=https://web.archive.org/web/20190716075426/https://www.demorgen.be/nieuws/eindelijk-zwart-op-wit-er-liggen-amerikaanse-kernwapens-in-belgie~b051dc18/|url-status=dead|title=Eindelijk zwart op wit: er liggen Amerikaanse kernwapens in België|first=Ann|last=De Boeck|date=July 16, 2019|archive-date=July 16, 2019|website=De Morgen))</ref> In 2012, NATO agreed to improve the capabilities of this force with the increased accuracy of the Mod 12 upgrade and the delivery of the F-35 aircraft.<ref>Kristensen, Hans M. [https://fas.org/blog/ssp/2012/05/nonstrategicnukes.php "New Report: US and Russian Non-Strategic Nuclear Weapons."] ((Webarchive|url=https://web.archive.org/web/20130130145337/http://www.fas.org/blog/ssp/2012/05/nonstrategicnukes.php |date=2013-01-30 )) Federation of American Scientists, 2 May 2012.</ref><ref>((cite web |url=https://www.theguardian.com/world/2013/apr/21/obama-accused-nuclear-guided-weapons-plan |title=Obama accused of nuclear U-turn as guided weapons plan emerges |last1=Borger |first1=Julian |date=21 April 2013 |work=The Guardian |access-date=11 June 2013 |archive-url=https://web.archive.org/web/20131104140851/http://www.theguardian.com/world/2013/apr/21/obama-accused-nuclear-guided-weapons-plan |archive-date=4 November 2013 |url-status=live ))</ref> This added a modest [[Standoff (missile)|standoff]] capability to the B61.<ref>((cite web |url=http://blogs.fas.org/security/2013/10/b61-12hearing/ |title=Capabilities of B61-12 Nuclear Bomb Increase Further |last1=Kristensen |first1=Hans M. |date=30 October 2013 |publisher=[[Federation of American Scientists]] |access-date=30 October 2013 |archive-url=https://web.archive.org/web/20131101064344/http://blogs.fas.org/security/2013/10/b61-12hearing/ |archive-date=2013-11-01 |url-status=dead ))</ref> The F-35A was certified to carry the B61-12 in October 2023, marking the first time a [[fifth generation fighter]] has been nuclear capable, and the first new platform in the NATO inventory to achieve such status since the early 1990s.<ref>[https://breakingdefense.com/2024/03/exclusive-f-35a-officially-certified-to-carry-nuclear-bomb/ EXCLUSIVE: F-35A officially certified to carry nuclear bomb]. ''Breaking Defense''. 8 March 2024.</ref>

==Design==
[[File:B61 nuclear bomb - inert training version.jpg|thumb|Inert training version of a B61 in an underground [[Weapons Storage and Security System]] (WS3) vault at [[Volkel Air Base]], Netherlands. An access panel on the warhead is open, showing the interface for actions such as [[Permissive Action Link|PAL (safety/arming)]] and [[variable yield]] setting]]

The B61 is a [[variable yield]] ("dial-a-yield" colloquially) dual use tactical and strategic bomb equipped with Full Fuzing Option (FUFO)<ref name=b61history/> designed for external carriage by high-speed aircraft. It has a streamlined casing capable of withstanding supersonic flight. The original B61-0 weapon was ((convert|141.6|in|m)) long, with a diameter of ((convert|13.3|inch|mm)) and a basic weight of ((convert|715|lb|kg))<ref name=b61history/> with most later weapons having approximately the same dimensions and weight,<ref name=NukeArchive/> except for the Mod 11 version which has a weight of approximately ((convert|1200|lb|kg)).<ref name=Nuke2005>((cite web |url=http://www.nukestrat.com/us/afn/B61-11.htm |title=the nuclear information project: the B61-11 |publisher=Nukestrat.com |access-date=2012-06-09 |archive-url=https://web.archive.org/web/20120910125852/http://www.nukestrat.com/us/afn/B61-11.htm |archive-date=2012-09-10 |url-status=live ))</ref>

===Ground operations===

The B61 is armed by ground-based personnel via an access panel located on the side of the bomb, which opens to reveal nine dials, two sockets, and a T-handle which manually triggers the "command disable" function. One of the sockets is for a MC4142 "strike enable" plug which must be inserted in order to complete critical circuits in the safety/arming and firing mechanisms. The other socket is the [[Permissive Action Link|PAL]] connector, which has 23 pins marked with alphabetic letter codes.<ref name=Glenn>((cite web |url=http://www.glennsmuseum.com/controller/controller.html |title=Glenn's Computer Museum-B61 Preflight Controller |publisher=Glennsmuseum.com |access-date=2012-07-08 |archive-url=https://web.archive.org/web/20120425133204/http://www.glennsmuseum.com/controller/controller.html |archive-date=2012-04-25 |url-status=live ))</ref>

The B61 "command disable" mechanism functions as follows: after entering the correct three-digit numeric code it is then possible to turn a dial to "DI" and pull back a T-shaped handle which comes away in the user's hand. This action releases a spring-loaded [[firing pin]] which fires the [[percussion cap]] on an MC4246A [[Molten-salt battery|thermal battery]], powering it up. Electrical power from the thermal battery is sufficient to "fry" the internal circuitry of the bomb, destroying critical mechanisms without causing detonation. This makes the bomb incapable of being used. Any B61 which has had the command disable facility activated must be returned to [[Pantex]] for repair.<ref name=Glenn/>

===Fuzing and delivery===

The B61 can be set for airburst or groundburst detonation, and by [[free fall]], retarded free fall or [[laydown delivery]] through the use of a [[parachute]] to slow down the weapon during release from the delivery aircraft.<ref name=b61history/> Only the Mod 0 to 10 versions of the B61 are equipped with a parachute retarder (currently a 24-ft (7.3 m) diameter [[nylon]]/[[Kevlar]] chute). This offers the aircraft a chance to escape the blast in its retarded delivery modes, or allows the weapon to survive impact with the ground in [[laydown]] delivery mode. [[Contact preclusion]] can also be selected by the pilot. The weapon can be released at speeds up to Mach 2 and altitudes as low as ((convert|50|ft|m)). In one of the weapon's laydown modes, it detonates 31 seconds after weapon release.<ref>((cite AV media |date=1970s |title=Developing and Producing the B-61 |language=en |url=https://www.youtube.com/watch?v=RlH7OuWiPb4 |access-date=10 July 2017 |time=11m 56s |publisher=US Department of Energy |archive-url=https://web.archive.org/web/20161212221529/https://www.youtube.com/watch?v=RlH7OuWiPb4 |archive-date=12 December 2016 |url-status=live ))</ref> 

The Mod 11 is a hardened penetration bomb with a reinforced casing and a delayed-action [[fuze]]; this allows the weapon to penetrate several metres into the ground before detonating, damaging fortified structures further underground. Developed from 1994, the Mod 11 went into service in 1997 replacing the older [[TNT equivalent|megaton]]-yield [[B53 bomb]]. About 50 Mod 11 bombs have been produced, their warheads converted from Mod 7 bombs. At present, the primary carrier for the Mod 11 is the [[B-2 Bomber|B-2 Spirit]].<ref name=Nuke2005/>

===Mods===

As of 2023, the B61 has 13 variants, referred to as Mod 0 through Mod 12.

{|class="wikitable"
|-
! Mod
! Status
! Date<ref group=Note>In this context, date means from the start of Phase 6 full scale production to the retirement of the final weapon at the end of Phase 7.</ref>
! Number produced
! Role
! Yields
! PAL type
! Notes
|-
| 0
| Retired
| 1/67 to 9/93<ref name=SandiaHistory/>
| 500<ref name=Kristensen2015>((cite journal |title=The B61 family of nuclear bombs |journal = Bulletin of the Atomic Scientists|volume = 70|issue = 3|pages = 79–84|last1=Kristensen |first1=Hans |last2=Norris |first2=Robert |date=27 November 2015 |doi=10.1177/0096340214531546 |s2cid = 146744069))</ref>
| Tactical<ref name=B61-7Dev>((cite report |date=1985 |title=Final Development Report for the B61-7 Bomb |publisher=Sandia National Laboratories |number=SAND85-0474))</ref>
| 10 to 300((nbsp))kt<ref name=Kristensen2015/>
| Cat B<ref name=NukeNotebook>((cite journal |first1=Robert |last1=Norris |first2=Hans |last2=Kristensen |first3=Joshua |last3=Handler |date=January 2003 |title=The B61 family of bombs |journal=Bulletin of the Atomic Scientists |volume=59 |issue=1 |url=http://journals.sagepub.com/doi/pdf/10.2968/059001020 |publisher=Bulletin of the Atomic Scientists January/February 2003 |pages=74–76 |doi=10.2968/059001020 |bibcode=2003BuAtS..59a..74N |s2cid=144014537 |access-date=2018-09-22 |archive-date=2021-08-31 |archive-url=https://web.archive.org/web/20210831071302/https://journals.sagepub.com/doi/pdf/10.2968/059001020 |url-status=live ))</ref>
| First production weapons
|-
| 1
| Retired
| 2/69 to 9/89<ref name=SandiaHistory/>
| 700<ref name=Kristensen2015/>
| Strategic<ref name=B61-7Dev/>
| 10 to 340((nbsp))kt<ref name=Kristensen2015/>
| None<ref name=NukeNotebook/><ref name=Kristensen2015/>
| 
|-
| 2
| Retired
| 6/75 to 9/94<ref name=SandiaHistory/>
| 235<ref name=Kristensen2015/>
| Tactical<ref name=B61-7Dev/>
| 10 to 150((nbsp))kt<ref name=Kristensen2015/>
| Cat D<ref name=Kristensen2015/>
|
|-
| 3
| Active
| 10/79 to present<ref name=SandiaHistory/>
| 545<ref name=Kristensen2015/>
| Tactical<ref name=Kristensen2015/>
| 0.3, 1.5, 60, or 170((nbsp))kt<ref name=NukeArchive/>
| Cat F<ref name=Kristensen2015/>
| 
|-
| 4
| Active
| 8/79 to present<ref name=SandiaHistory/>
| 695<ref name=Kristensen2015/>
| Tactical<ref name=Kristensen2015/>
| 0.3, 1.5, 10, or 45((nbsp))kt<ref name=NukeArchive/>
| Cat F<ref name=Kristensen2015/>
| 
|-
| 5
| Retired
| 6/77 to 9/93<ref name=SandiaHistory/>
| 265<ref name=Kristensen2015/>
| Tactical<ref name="Reliability">((cite report |author=R E Kidder |date=26 July 1991 |title=Report to Congress: Assessment of the Safety of US Nuclear Weapons and Related Nuclear Test Requirements |url=https://fas.org/programs/ssp/nukes/testing/kidderucrllr107454.pdf |publisher=[[Lawrence Livermore National Lab]] |access-date=22 March 2021 |archive-date=24 December 2012 |archive-url=https://web.archive.org/web/20121224222103/http://www.fas.org/programs/ssp/nukes/testing/kidderucrllr107454.pdf |url-status=live ))</ref><ref name=B61-7Dev/>
| 10 to 150((nbsp))kt<ref name=NukeNotebook/>
| Cat D<ref name=Kristensen2015/>
| 
|-
| 6
| Never entered production
|
| 
| 
| 10 to 150((nbsp))kt<ref name=Kristensen2015/>
| Cat D<ref name=Kristensen2015/>
| Conversion of Mod 0.<ref name=NukeNotebook/> Cancelled February 1992.<ref name=SandiaHistory/>
|-
| 7
| Active
| 9/85 to present<ref name=SandiaHistory/>
| 600<ref name=Kristensen2015/>
| Strategic
| Allegedly 4 yield settings, including 10, or 340((nbsp))kt.<ref name=NukeArchive/>
| Cat D<ref name=Kristensen2015/>
| Conversion of Mod 1, conversion completed by April 1990<ref name=NukeNotebook/>
|-
| 8
| Never entered production
|
| 
| 
| 10 to 150((nbsp))kt<ref name=Kristensen2015/>
| Cat D<ref name=Kristensen2015/>
| Conversion of Mod 2 and Mod 5.<ref name=NukeNotebook/> Cancelled February 1992.<ref name=SandiaHistory/>
|-
| 9
| Never entered production
|
| 
| 
| 10 to 300((nbsp))kt<ref name=Kristensen2015/>
| Cat F<ref name=Kristensen2015/>
| Conversion of Mod 0.<ref name=NukeNotebook/> Cancelled September 1991.<ref name=SandiaHistory/>
|-
| 10
| Inactive stockpile
| 8/90 to present<ref name=SandiaHistory/>
| 215<ref name=Kristensen2015/>
| Tactical
| 0.3, 5, 10, or 80((nbsp))kt<ref name=NukeArchive/>
| Cat F<ref name=Kristensen2015/>
| Remanufactured from retired [[Pershing II]] [[W85 (nuclear warhead)|W85 warheads]].<ref name=NukeNotebook/>
|-
| 11
| Active
| 12/96 to present<ref name=SandiaHistory/>
| 50<ref name=Kristensen2015/>
| Strategic
| Disputed, either same as Mod 7<ref name=NukeArchive/> or 400((nbsp))kt<ref name=Kristensen2015/>
| Cat F<ref name=Kristensen2015/>
| Conversion of Mod 7, earth penetrating weapon.<ref name=NukeNotebook/>
|-
| 12
| Active
| First production unit 11/21<ref name=FPU>((Cite web| title = NNSA Completes First Production Unit of B61-12 Life Extension Program| work = Energy.gov| accessdate = 2022-11-19| url = https://www.energy.gov/nnsa/articles/nnsa-completes-first-production-unit-b61-12-life-extension-program| archive-date = 2022-10-04| archive-url = https://web.archive.org/web/20221004134229/https://www.energy.gov/nnsa/articles/nnsa-completes-first-production-unit-b61-12-life-extension-program| url-status = live))</ref>
| 400 to 500 weapons planned
| Tactical/Strategic<ref>((cite web |url=https://nnsa.energy.gov/sites/default/files/nnsa/factsheet/b61-12_lep.pdf |title=B61-12 Life Extension Program |access-date=2018-02-03 |archive-url=https://web.archive.org/web/20170515075732/https://nnsa.energy.gov/sites/default/files/nnsa/factsheet/b61-12_lep.pdf |archive-date=2017-05-15 |url-status=dead ))</ref><ref>((cite web |url=https://fas.org/programs/ssp/nukes/publications1/Brief2014_PREPCOM2.pdf |title=B61-12: The New Guided Standoff Nuclear Bomb |access-date=2018-02-03 |archive-url=https://web.archive.org/web/20171202210329/https://fas.org/programs/ssp/nukes/publications1/Brief2014_PREPCOM2.pdf |archive-date=2017-12-02 |url-status=live ))</ref><ref>((Cite book| url=https://books.google.com/books?id=ZqPmAgAAQBAJ&q=b61+12+strategic&pg=PA262| title=Nuclear Scholars Initiative: A Collection of Papers from the 2013 Nuclear Scholars Initiative| isbn=9781442227989| last1=Weiner| first1=Sarah| date=2014-01-27| publisher=Rowman & Littlefield| access-date=2020-10-25| archive-date=2021-08-31| archive-url=https://web.archive.org/web/20210831071302/https://books.google.com/books?id=ZqPmAgAAQBAJ&q=b61+12+strategic&pg=PA262| url-status=live))</ref>
| 0.3, 1.5, 10, or 50((nbsp))kt<ref name=Kristensen2015/><ref>((cite web |url=https://fas.org/blogs/security/2016/01/b61-12_earth-penetration/ |title=Video Shows Earth-Penetrating Capability of B61-12 Nuclear Bomb |access-date=2016-06-04 |archive-url=https://web.archive.org/web/20160630033533/http://fas.org/blogs/security/2016/01/b61-12_earth-penetration |archive-date=2016-06-30 |url-status=live ))</ref>
| Cat F<ref name=Kristensen2015/>
| Conversion of Mod 4.<ref name=Kristensen2015/> To replace the Mods 3, 4 and 7.<ref name=FPU/>
|-
| 13
| 
| 
| "a few dozen"
| Tactical/Strategic
| Allegedly 4 yield settings, including 10, or 340((nbsp))kt.
|
| Conversion of Mod 7, earth penetrating weapon.<ref name=NukeNotebook/>|Conversion of Mod 7, earth penetrating weapon.<ref name=NukeNotebook/>
|}

===B61 Mod 3 and 4===
[[File:B61internals.png|thumb|right|Internal nuclear components of the B61 bomb. The bomb was assembled at the [[Burlington AEC Plant]] and [[Pantex]].]]
A Sandia document on the dates of the development phases of the US nuclear stockpile describes the B61-3 as an "improved Mod 2 w/IHE" and the B61-4 as "same as Mod 3 ex. Hi-Y".<ref name=SandiaHistory>((cite report |author=Terry Michael Josserand |date=1 March 2017 |title=R&A for UUR_Weapon_History_Phases_20170206. |url=https://www.osti.gov/biblio/1429158-uur_weapon_history_phases_20170206 |publisher=Sandia National Labs |page= |docket= |access-date=30 August 2021 |quote= |osti=1429158 |archive-date=30 August 2021 |archive-url=https://web.archive.org/web/20210830022145/https://www.osti.gov/biblio/1429158-uur_weapon_history_phases_20170206 |url-status=live ))</ref>

The B61 Mod 3 and 4 bombs do not contain [[beryllium]].<ref name=Beryllium>((cite report |date=1 May 1978 |title=Special Task Group Report – Beryllium: Substitute Materials for Be and BeO in Nuclear Weapons Volume II – Impact on United States Department of Energy National Defense Programs of proposed Department of Labor (Occupational Health and Safety Administration) Beryllium Standards |url=https://osf.io/kpcy8/ |publisher=United States Department of Energy |quote="Of the LASL devices currently entering stockpile, the B61-3 and B61-4 do not contain beryllium. The B61-5 does, but the B61-3 could probably be substituted for it." |access-date=7 June 2021 |archive-date=7 June 2021 |archive-url=https://web.archive.org/web/20210607041334/https://osf.io/kpcy8/ |url-status=live ))</ref>

===B61 Mod 5===
A 1978 report on reducing or substituting beryllium in nuclear weapons noted that the B61-5 contained beryllium and that if the use of beryllium were to be restricted, the B61-5 could probably be replaced by the B61 Mod 3.<ref name=Beryllium/>

===B61 Mod 6 and 8===
The B61 Mod 6 and Mod 8 bombs were developed for use by the US Navy beginning in March 1987<ref name=Mod68>((cite report |date=May 1989 |title=Interim Development Report for the B61-6,8 Bombs |url=https://osf.io/g84bs/ |publisher=Sandia National Laboratories and Los Alamos National Labs |page=9 |docket=SAND88-2986 |access-date=2021-05-28 |archive-date=2021-07-20 |archive-url=https://web.archive.org/web/20210720120116/https://osf.io/g84bs/ |url-status=live |ref=((harvid|Interim Development Report for the B61-6,8 Bombs)) ))</ref> and cancelled at the end of the Cold War.<ref name=Kristensen2015/> The weapons weighed ((convert|350|kg|lb)), had a length of ((convert|3597|mm|inch)) and a diameter of ((convert|338|mm|inch)), and were one-point safe, used insensitive high explosives (IHE) in their primary stages and utilized enhanced electrical safety (EES).((sfn|Interim Development Report for the B61-6,8 Bombs|p=9)) 

The weapons were to be built by converting existing B61-0, −2 and −5 weapons into Mod 6 and 8 weapons and the weapons were to use B61-7 weapon parts where possible.((sfn|Interim Development Report for the B61-6,8 Bombs|p=11)) By mass, the largest deviations from the B61-7 were the Acorn assembly, MC4137 TSSG (trajectory sensing signal generator) and the JTA (described as "ballast for WR").((sfn|Interim Development Report for the B61-6,8 Bombs|p=16))

====Electrical systems====
The weapon's computer was the MC4139 Programmer, two of which are used on independent channels, and is identical to the programmer used on the B61-7.((sfn|Interim Development Report for the B61-6,8 Bombs|p=21)) The MC3656 Main Battery is identical to the battery used on the B61-7 and is thermally operated, providing 120 seconds of power for the weapon,((sfn|Interim Development Report for the B61-6,8 Bombs|p=26)) but initial power is supplied by the MC2238 Pulse Batteries which are activated by the weapon's pullout switches during separation from the aircraft.((sfn|Interim Development Report for the B61-6,8 Bombs|p=31))

The weapon contained two neutron generators for initiation,((sfn|Interim Development Report for the B61-6,8 Bombs|p=17)) used a 2400 volt 0.6 μF capacitor for neutron generator firing and a 3300 volt 2.0 μF capacitor for the firing set.((sfn|Interim Development Report for the B61-6,8 Bombs|p=36)) If neither the radar fuze or the contact crystals actuated, the weapon would detonate at 120 seconds from arming.((sfn|Interim Development Report for the B61-6,8 Bombs|p=37))

The weapons were to initially use the MC4175 Trajectory Sensing Signal Generators which are identical to the TSSG found in the B61-7, but starting from 1991, the Mod 6 was to get a new MC4137 Trajectory Sensing Signal Generator. The MC4175 stored the arming signal for the trajectory [[Strong link/weak link|stronglink]] it its memory, so it featured a pair of [[rolamite]] acceleration switches designed to prevent the possibility of the signal being transferred to the stronglink before the rolamites were actuated by the spinning of the weapon in flight.((sfn|Interim Development Report for the B61-6,8 Bombs|p=22)) The MC4137 instead is provided the unique signal from the MC4139 Programmer, which stores it in a volatile memory that erases after approximately seven seconds of lost power, meaning that without intent from the MC4139 and continuously applied power the MC4137 does not know how to arm the safelink.((sfn|Interim Development Report for the B61-6,8 Bombs|p=48-50))

====Stronglink switches and weaklinks====
[[File:B61-6,8 IUQS for MC2969.png|thumb|IUQS for MC2969 Intent Stronglink Switch]]
The weapon was to feature a number of weapon stronglinks. Stronglinks are part of the weapon's safety systems and are designed to be robust enough that they can survive abnormal environments long enough for the weapon's weaklinks to fail. This requires weak and stronglinks to be colocated so they are exposed to the same environmental conditions in an accident.((sfn|Interim Development Report for the B61-6,8 Bombs|p=41))

The first stronglink was the MC2969 Intent Stronglink Switch which was also used on the B61-3, −4 and −7, W78, W80 and B83 weapons. The MC2969 consisted of a 14-pin ceramic-insulated bank of switches that would close upon the receipt of the proper intent unique signal (IUQS) to its electromechanical decoder. Receipt of the wrong signal would lock the MC2969 in the open position until a specific unlock signal was received.((sfn|Interim Development Report for the B61-6,8 Bombs|p=18))

The second stronglink was the MC2935 Trajectory Stronglink Switch of which there were two, one for each channel of the weapon's firing set. Like the MC2969, it mechanically locked if it received the wrong input signals, but unlike the MC2969 it could only be manually unlocked, which could only take place at the factory.((sfn|Interim Development Report for the B61-6,8 Bombs|p=19, 43)) Signals for the MC2935 come from either of the two MC4175s or the MC4137 Trajectory Sensing Signal Generators.((sfn|Interim Development Report for the B61-6,8 Bombs|p=17))

A third stronglink existed inside the first exclusion region of the weapon and was involved in weapon arming. Details of the system are still classified.((sfn|Interim Development Report for the B61-6,8 Bombs|p=42-43))

===B61 Mod 12===
[[File:F-35 B61-12 trial.jpg|thumb|B61 Mod 12 test]]

As of 2013 the Pentagon saw the [[B83 nuclear bomb]] as a "relic of the Cold War," believing that deploying a megaton-yield gravity bomb, the highest level nuclear weapon left in the U.S. inventory, to Europe was "inconceivable" at this point. It can also only be carried by the B-2 bomber, and integrating it onto additional aircraft would be costly. The Mod 12 upgrade is being pursued as a forward-deployed tactical/strategic nuclear weapon to protect NATO and Asian allies since it can be used from dual-capable fighter aircraft, as well as planned to arm the F-35 and [[B-21 Raider]], and its lower yield options make it more flexible with less collateral effects. Recapitalizing the B61 is hoped to lead to the retirement of the B83, resulting in the elimination of the last megaton-yield U.S. bomb and leave the B61-series as the only U.S. gravity nuclear bomb.<ref>((Citation | url = http://www.airforcemag.com/Features/Pages/2013/November%202013/box110413gravity.aspx | title = Cold War Relic | newspaper = Air force mag | date = 4 November 2013 | access-date = 23 January 2014 | archive-url = https://web.archive.org/web/20131109150243/http://www.airforcemag.com/Features/Pages/2013/November%202013/box110413gravity.aspx | archive-date = 9 November 2013 | url-status = live ))</ref>

In 2013, the Pentagon and NNSA stated that if B61 refurbishment did not begin by 2019, components in the existing weapons could begin to fail.<ref>((cite web|last=Reif|first=Kingston|title=Pentagon Pushes for Billions to Refurbish Nuclear Bombs|url=http://thebulletin.org/pentagon-pushes-billions-refurbish-nuclear-bombs|publisher=Bulletin of the Atomic Scientists|access-date=October 25, 2013|date=2013-10-25|archive-url=https://web.archive.org/web/20131029033910/http://thebulletin.org/pentagon-pushes-billions-refurbish-nuclear-bombs|archive-date=October 29, 2013|url-status=live))</ref> In 2013 Tom Collina of the [[Arms Control Association]] said that the new development could complicate arms control efforts with Russia.<ref>((cite news |url= https://www.google.com/hostednews/afp/article/ALeqM5jQQKVoqzhqtYpBYtg3oXJD6F1nFA?docId=08f741e1-b8fa-46e9-8c3c-84c549d8a156&hl=en |title= US to spend billions 'modernizing' nuclear arsenal |last= Rabechault |first= Mathieu |date= 6 November 2013 |agency= AFP |access-date= 7 November 2013 |archive-url= https://web.archive.org/web/20131119104135/https://www.google.com/hostednews/afp/article/ALeqM5jQQKVoqzhqtYpBYtg3oXJD6F1nFA?docId=08f741e1-b8fa-46e9-8c3c-84c549d8a156&hl=en |archive-date= 19 November 2013 |url-status= live ))</ref>

In 2014, Congress slashed funding for the project and called for alternates to be studied.<ref>((cite news |url=http://www.nti.org/gsn/article/nuclear-security-and-omnibus-legislation-whats-and-whats-down/ |title=Nuclear Security and Omnibus Legislation: What's Up and What's Down |last1=Guarino |first1=Douglas P. |date=16 January 2014 |publisher=Nuclear Threat Initiative |agency=Global Security Newswire |access-date=16 January 2014 |archive-url=https://web.archive.org/web/20140118225826/http://www.nti.org/gsn/article/nuclear-security-and-omnibus-legislation-whats-and-whats-down/ |archive-date=18 January 2014 |url-status=live ))</ref>
In January 2014, former Air Force Chief of Staff [[Norton A. Schwartz]] stated that the Mod 12 nuclear bomb upgrade would have enhanced accuracy and a lower yield with less fallout compared to previous versions of the weapon. Accuracy has not been a guarantee for air-dropped nuclear weapons, so consequently large warheads were needed to effectively impact a target; the Mod 11 nuclear earth-penetrator is accurate to 110–170 meters from the desired detonation location, so it requires a 400-kiloton warhead. The Mod 12 is accurate to 30 meters from a target and only requires a 50-kiloton warhead. Schwartz believes that greater accuracy would both improve the weapon and create a different target set it can be useful against. An example is the higher-yield Mod 11's role of attacking underground bunkers that need a ground burst to create a crater and destroy it through the shockwave. A 50-kiloton yield detonating on the ground produces a crater with a radius of 30–68 meters, depending on the density of the surface, effectively putting the bunker within the [[circular error probability]].<ref name="fas25nov14">((Citation | url = https://fas.org/blogs/security/2014/01/b61capability/ | title = General Confirms Enhanced Targeting Capabilities of B61-12 Nuclear Bomb | newspaper = Federation of American Scientists | publisher = Fas | date = 23 January 2014 | access-date = 12 December 2015 | archive-url = https://web.archive.org/web/20151222074122/https://fas.org/blogs/security/2014/01/b61capability/ | archive-date = 22 December 2015 | url-status = live ))</ref>

In 2014 critics said that a more accurate and less destructive nuclear weapon would make leaders less cautious about deploying it, while Schwartz said it would deter adversaries more because the U.S. would be more willing to use it in situations where necessary. The improved accuracy would make it more effective than the previous Mod 3/4 currently deployed to the continent. F-16 and Panavia Tornado aircraft cannot interface with the new bomb due to electronic differences, but NATO countries buying the F-35 would be able to utilize it.<ref name="fas25nov14"/> The first flight test for an inert Mod 12 was conducted in 2015, with a second successful test in August 2017.<ref>((cite news |url= http://nationalinterest.org/blog/the-buzz/america-russia-test-new-tactical-nuclear-missiles-13319 |title= America and Russia Test New Tactical Nuclear Missiles |last= Keck |first= Zachary |date= 13 July 2015 |website= National interest |publisher= The National Interest |access-date= 13 July 2015 |archive-date= 31 August 2021 |archive-url= https://web.archive.org/web/20210831071250/https://nationalinterest.org/blog/the-buzz/america-russia-test-new-tactical-nuclear-missiles-13319 |url-status= live ))</ref><ref name="flightglobal10july15">((Citation | url = http://www.flightglobal.com/news/articles/us-conducts-first-flight-test-of-guided-b61-12-nuclear-414484/ | title = US conducts first flight test of guided B61-12 nuclear bomb | publisher = Flight global | date = 10 July 2015 | access-date = 10 July 2015 | archive-url = https://web.archive.org/web/20150711110036/http://www.flightglobal.com/news/articles/us-conducts-first-flight-test-of-guided-b61-12-nuclear-414484/ | archive-date = 11 July 2015 | url-status = live ))</ref>

Despite claims the Mod 12 has an earth penetrating capability,<ref>[https://fas.org/blogs/security/2016/01/b61-12_earth-penetration/ Video Shows Earth-Penetrating Capability of Mod 12 Nuclear Bomb] ((Webarchive|url=https://web.archive.org/web/20160630033533/http://fas.org/blogs/security/2016/01/b61-12_earth-penetration |date=2016-06-30 )) – Fas.org, 14 January 2016</ref> the weapon does not have the reinforced structure like that of the Mod 11, which is required to function as an earth penetrating weapon. The Mod 11 will be retained in service for the ground penetrating mission.<ref>((cite news |url=https://nationalinterest.org/blog/buzz/air-force-really-testing-%E2%80%98earth-penetrating%E2%80%99-nuclear-bomb-58002 |title=Is the Air Force Really Testing an 'Earth-Penetrating' Nuclear Bomb? |last1=Miles |first1=Aaron |date=18 May 2019 |website=nationalinterest.org |publisher=Center for the National Interest |access-date=7 June 2019 |archive-url=https://web.archive.org/web/20190607180640/https://nationalinterest.org/blog/buzz/air-force-really-testing-%25E2%2580%2598earth-penetrating%25E2%2580%2599-nuclear-bomb-58002 |archive-date=7 June 2019 |url-status=live ))</ref>

The Mod 12 Life Extension Program continued in 2018 and on 29 June 2018 two successful non-nuclear system qualification flight tests at Tonopah Test Range were reported.<ref>[https://www.globalsecurity.org/wmd/library/news/usa/2018/usa-180629-nnsa01.htm/ NNSA, Air Force complete successful end-to-end Mod 12 Life Extension Program flight tests at Tonopah Test Range] ((Webarchive|url=https://web.archive.org/web/20180702073147/https://www.globalsecurity.org/wmd/library/news/usa/2018/usa-180629-nnsa01.htm |date=2018-07-02 )) GlobalSecurity.org</ref> In October 2018, the Mod 12 guided tail-kit assembly received Milestone C approval to enter the production phase; the TKA went through the traditional test program in under 11 months, achieving a 100% success rate for all 31 bomb drops.<ref>[http://www.airrecognition.com/index.php/archive-world-worldwide-news-air-force-aviation-aerospace-air-military-defence-industry/global-defense-security-news/global-news-2018/december/4682-us-air-force-s-b61-12-nuclear-bomb-new-guided-tail-kit-assembly-enters-production-phase.html US Air Force's Mod 12 nuclear bomb new guided tail-kit assembly enters production phase] ((Webarchive|url=https://web.archive.org/web/20181215142859/http://www.airrecognition.com/index.php/archive-world-worldwide-news-air-force-aviation-aerospace-air-military-defence-industry/global-defense-security-news/global-news-2018/december/4682-us-air-force-s-b61-12-nuclear-bomb-new-guided-tail-kit-assembly-enters-production-phase.html |date=2018-12-15 )). ''Air Recognition''. 10 December 2018.</ref> The B61-12 nuclear bomb completed its successful flight tests with the US Air Force's F-15E in June 2020. It was dropped from above 25,000ft and was in the air for approximately 55 seconds before hitting the target.<ref>((cite web|last=|first=|date=June 2020|title=B61-12|url=https://www.airforce-technology.com/projects/b61-12-nuclear-bomb/|access-date=|website=|archive-date=2021-01-26|archive-url=https://web.archive.org/web/20210126050400/https://www.airforce-technology.com/projects/b61-12-nuclear-bomb/|url-status=live))</ref>

The first B61-12 bomb was produced in November 2021. The weapon replaces the B61 mod 3, mod 4 and mod 7 bombs while the B61-11 will be retained in the stockpile. It is expected that the LEP will extend the B61's life by at least 20 years.<ref name=FPU/> ''[[Politico]]'' reported in October 2022 that the US military planned to accelerate the deployment of the Mod 12 in Europe.<ref name="SCMP Russia says US lowering nuclear threshold">((cite news |title=Russia says US lowering 'nuclear threshold' with newer bombs in Europe |url=https://www.scmp.com/news/world/russia-central-asia/article/3197739/russia-says-us-lowering-nuclear-threshold-newer-bombs-nato-bases-europe |access-date=29 October 2022 |work=South China Morning Post |date=30 October 2022 |language=en |archive-date=29 October 2022 |archive-url=https://web.archive.org/web/20221029171505/https://www.scmp.com/news/world/russia-central-asia/article/3197739/russia-says-us-lowering-nuclear-threshold-newer-bombs-nato-bases-europe |url-status=live ))</ref> This drew criticism from the Russian Deputy Minister of Foreign Affairs [[Alexander Grushko]], who accused the US government of "reducing the nuclear threshold" with the weapon's increased accuracy.<ref name="SCMP Russia says US lowering nuclear threshold"/>

The [[F/A-18E/F Super Hornet]] is not listed as a future platform.<ref>((cite web |last=Kristensen |first=Hans |url=https://fas.org/blogs/security/2021/12/fa-18_removed-from-fact-sheet/ |title=NNSA Removes F/A-18F Super Hornet From Nuclear Bomb Fact Sheet – Federation Of American Scientists |publisher=Fas.org |date=2021-12-15 |accessdate=2022-03-09 |archive-date=2022-02-12 |archive-url=https://web.archive.org/web/20220212175214/https://fas.org/blogs/security/2021/12/fa-18_removed-from-fact-sheet/ |url-status=live ))</ref>

===B61 Mod 13===
Initially, the NNSA Stockpile Stewardship and Management Plan anticipated Phase 1 development for the B61 Mod 13 Life Extension Program (LEP) beginning in 2037 with first production of the weapon in 2050,<ref name=SandiaHistory/> but in 2023 plans were announced to produce a new gravity bomb similar to that of the B61-12, but having a high yield similar to that of the B61-7, named the B61 Mod 13.<ref>((Cite web| title = Department of Defense Announces Pursuit of B61 Gravity Bomb Variant| work = U.S. Department of Defense| accessdate = 2023-10-28| url = https://www.defense.gov/News/Releases/Release/Article/3571660/department-of-defense-announces-pursuit-of-b61-gravity-bomb-variant/https%3A%2F%2Fwww.defense.gov%2FNews%2FReleases%2FRelease%2FArticle%2F3571660%2Fdepartment-of-defense-announces-pursuit-of-b61-gravity-bomb-variant%2F))</ref> This discards plans for the Mod 13 to be a future Mod 12 LEP.<ref name=FAS_mod13>((Cite web| title = Biden Administration Decides To Build A New Nuclear Bomb to Get Rid Of An Old Bomb| work = Federation of American Scientists| accessdate = 2023-10-28| url = https://fas.org/publication/biden-administration-to-build-a-new-nuclear-bomb/| archive-date = 2023-10-27| archive-url = https://web.archive.org/web/20231027232238/https://fas.org/publication/biden-administration-to-build-a-new-nuclear-bomb/| url-status = live))</ref> It is planned that for each B61-13 produced, one fewer B61-12 is to be produced, therefore not increasing the planned number of new B61 bombs;<ref>((Cite report| last = US Department of Defense| title = Fact Sheet on B61 Variant Development| accessdate = 2023-10-28| url = https://media.defense.gov/2023/Oct/27/2003329624/-1/-1/1/B61-13-FACT-SHEET.PDF| archive-date = 2023-10-27| archive-url = https://web.archive.org/web/20231027204916/https://media.defense.gov/2023/Oct/27/2003329624/-1/-1/1/B61-13-FACT-SHEET.PDF| url-status = live))</ref> defense officials indicated only "a few dozen" B61-13s may be produced. The new bomb will be carried by the [[B-21 Raider]], but it is not planned to be deployed on the F-35.<ref>[https://www.defensenews.com/pentagon/2023/10/27/us-to-build-new-nuclear-gravity-bomb/ US to build new nuclear gravity bomb]. ''[[Defense News]]''. 27 October 2023.</ref>

The Federation of American Scientists have accused the weapon of being a "political bomb", introduced to finally retire the B83-1 nuclear bomb, whose retirement has been blocked by hardliners.<ref name=FAS_mod13/>

===W61 Earth Penetrator Warhead===
[[File:W61 Earth Penetrator Warhead.jpg|thumb|W61 Nuclear Earth Penetrator Warhead]]

A W61 Earth Penetrator Warhead (EPW) with a yield of ((convert|340|ktTNT)) was developed for the [[AGM-129 ACM|AGM-129 Advanced Cruise Missile]] and the [[MGM-134 Midgetman]] small ICBM. The weapon entered Phase 1 initial development in January 1985 and phase 4 production engineering in September 1992 before being cancelled in December of that year.<ref name=Kristensen2015/><ref name=SandiaHistory/><ref name=Sure1988>((cite report |date=September 1989 |title=Nuclear Weapons Surety – Annual Report to the President 1988 |url=https://documents.theblackvault.com/documents/nuclear/NuclearWeaponsSurety1988.pdf |publisher=Department of Defense and Department of Energy |page=63 |docket= |access-date= |quote="ACM[EPW]/W61 schedule for which Phase 2A has been completed (Phase 3 is planned in the next few months) and will permit the removal of the B53 from standing alert." |archive-date=2022-03-05 |archive-url=https://web.archive.org/web/20220305040546/https://documents.theblackvault.com/documents/nuclear/NuclearWeaponsSurety1988.pdf |url-status=live ))</ref>

In the Advanced Cruise Missile role, the weapon was to replace aging B53 bombs, but after the W61 cancellation the role was filled by the B61-11 bomb.<ref name=Sure1988/>

===Pits===

A declassified technical report on the automation of pit handling at [[Pantex]] indicates that the B61-2 and B61-5 share a common [[Pit (nuclear weapon)|pit]] design, as do the B61-3, B61-10 and W85. The B61-0 and B61-4 do not share a pit with any other weapon. As the B61-7 was a retrofit of the B61-1 and the B61-11 was a retrofit of the B61-7, they presumably share a common pit.<ref>((cite report |author=Fahrenholtz, Jill C |date=September 1997 |title=Development of an Automated Pit Packaging System for Pantex |url=https://pdfs.semanticscholar.org/81d2/cef59b611d653b022d451b8d687ba3df5e47.pdf |archive-url=https://web.archive.org/web/20200215190559/https://pdfs.semanticscholar.org/81d2/cef59b611d653b022d451b8d687ba3df5e47.pdf |url-status=dead |archive-date=2020-02-15 |publisher=Sandia National Labs |page=15 |doi=10.2172/534478 |s2cid=107183716 |docket=SAND 97-2163 |access-date=2021-02-09))</ref>

==Cost==
In May 2010 the National Nuclear Security Administration asked Congress for $40 million to redesign the bomb to enable the [[Lockheed Martin F-35 Lightning II]] to carry the weapon internally by 2017.<ref>((Citation | url = http://www.globalsecuritynewswire.org/gsn/nw_20100518_1164.php | date = May 18, 2010 | title = NNSA Seeks $40M for Nuke Refurbishment Study | newspaper = Global security news wire | access-date = May 19, 2010 | archive-url = https://web.archive.org/web/20100706201423/http://www.globalsecuritynewswire.org/gsn/nw_20100518_1164.php | archive-date = July 6, 2010 | url-status = live ))</ref> This version is designated Mod 12.<ref>((Citation | url = http://bos.sagepub.com/content/67/1/64.full.pdf | publisher = Sage pub | title = US tactical nuclear weapons in Europe | journal = Bulletin of the Atomic Scientists | year = 2011 | volume = 67 | issue = 1 | pages = 64–73 | doi = 10.1177/0096340210393931 | access-date = 2011-01-18 | archive-url = https://web.archive.org/web/20110603065306/http://bos.sagepub.com/content/67/1/64.full.pdf | archive-date = 2011-06-03 | url-status = live | last1 = Norris | first1 = Robert S. | last2 = Kristensen | first2 = Hans M. | s2cid = 54186148 | doi-access = free ))</ref> The four hundred Mod 12 bombs will be used by both tactical aircraft (such as the F-35) and strategic aircraft (such as the B-2) and the Tail Subassembly (TSA) will give them [[Joint Direct Attack Munition]] levels of accuracy, allowing the fifty kiloton warhead to have strategic effects from all carrying aircraft.<ref>Kristensen, Hans. [https://fas.org/blogs/security/2011/06/b61-12/ "B61 LEP: Increasing NATO Nuclear Capability and Precision Low-Yield Strikes."] ((Webarchive|url=https://web.archive.org/web/20160915023757/http://fas.org/blogs/security/2011/06/b61-12/ |date=2016-09-15 )) ''FAS'', 15 June 2011.</ref> However, refitting the 400 weapons is now expected to cost over $10 billion.<ref>Kristensen, Hans. [https://fas.org/blog/ssp/2012/07/b61-12gold.php "B61-12: NNSA’s Gold-Plated Nuclear Bomb Project."] 26 July 2012((Webarchive|url=https://web.archive.org/web/20130116152834/http://www.fas.org/blog/ssp/2012/07/b61-12gold.php |date=2013-01-16 )) ''FAS'', 26 July 2012.</ref> The Mod 12 tail assembly contract was awarded to [[Boeing]] on November 27, 2012 for $178 million.<ref>((Citation | url = http://www.deagel.com/news/Boeing-to-Upgrade-B61-Nuclear-Free-Fall-Bomb_n000010996.aspx | title = Boeing to Upgrade B61 Nuclear Free Fall Bomb | publisher = Deagel | date = November 27, 2012 | access-date = November 28, 2012 | archive-url = https://web.archive.org/web/20130406182329/http://www.deagel.com/news/Boeing-to-Upgrade-B61-Nuclear-Free-Fall-Bomb_n000010996.aspx | archive-date = April 6, 2013 | url-status = live ))</ref> Boeing will use their experience with the Joint Direct Attack Munition to yield JDAM-equivalent accuracy in a nuclear bomb.<ref>((Citation | publisher = Media room | url = http://boeing.mediaroom.com/index.php?s=43&item=2510 | title = Boeing Receives $178 Million Contract for B61 Tail Kit Assembly | access-date = 2012-12-02 | archive-url = https://web.archive.org/web/20121203201541/http://boeing.mediaroom.com/index.php?s=43&item=2510 | archive-date = 2012-12-03 | url-status = live ))</ref> This contract is only the first part of the billion-dollar expense of producing and applying the tail kits, over and above the $10 billion cost to refurbish the warheads.<ref>Kristensen, Hans.  [http://blogs.fas.org/security/2013/04/b61-12tail/ "$1 Billion for a Nuclear Bomb Tail."] ((Webarchive|url=https://web.archive.org/web/20130718180722/http://blogs.fas.org/security/2013/04/b61-12tail/ |date=2013-07-18 )) ''FAS'', 12 April 2013.</ref> The Mod 12 uses an internal guidance system and can glide to its target. On 1 July 2015, the [[National Nuclear Security Administration]] (NNSA) conducted the first of three flight tests of the Mod 12 tail kit assembly.<ref name="flightglobal10july15"/>

According to the [[Federation of American Scientists]] in 2012, the roughly 400 B61-12s will cost $28 million apiece.<ref name=FAS12/>

==See also==
[[Image:B-61 bomb rack.jpg|thumb|B61s on a bomb rack|alt=]]
* [[B61 Family]]
* [[List of nuclear weapons]]
* [[WE.177]]
* [[Weapons Storage and Security System]]

((clear))

==Notes==
((reflist|group=Note))

==References==
((Reflist|30em))

==External links==
((Commonscatinline))
* ((Citation | url = https://www.nytimes.com/2016/01/12/science/as-us-modernizes-nuclear-weapons-smaller-leaves-some-uneasy.html | type = information<!-- long-form journalism piece; not sure if the type should change here --> | title = As U.S. Modernizes Nuclear Weapons, 'Smaller' Leaves Some Uneasy | date = 11 January 2016 | work =The New York Times)).
* ((Citation | url = https://www.youtube.com/watch?v=RlH7OuWiPb4 | title = Developing and Producing the B-61 | publisher = AEC | format = Google You tube)).
* ((Citation | url = http://www.globalsecurity.org/wmd/systems/b61.htm | contribution = B61 | type = information | title = Weapons of mass destruction | publisher = Global Security)).
* ((Citation | url = http://lasg.org/archive/1997/b61-11.htm | title = B61-11 Concerns and Background | publisher = Los Alamos Study Group | year = 1997)), an anti-nuclear weapons organization
* ((Citation | url = https://fas.org/faspir/2001/v54n1/weapons.htm | title = Low-Yield Earth-Penetrating Nuclear Weapons | journal = Science and Global Security | first = Robert W | last = Nelson | publisher = Federation of American Scientists | date = January–February 2001 | volume = 54 | pages = 1–20 | number = 1| bibcode = 2002S&GS...10....1N | doi = 10.1080/08929880212326 | s2cid = 123478310 )).
* ((Citation | url = http://www.thebulletin.org/article_nn.php?art_ofn=jf03norris | title = The B61 family of bombs | first1 = Robert S | last1 = Norris | first2 = Hans M | last2 = Kristensen | first3 = Joshua | last3 = Handler | journal = [[Bulletin of the Atomic Scientists]] | volume = 59 | issue = 1 | pages = 74–76 | year = 2003 | doi = 10.2968/059001020 | bibcode = 2003BuAtS..59a..74N | s2cid = 144014537 | access-date = 2006-01-16 | archive-date = 2006-09-28 | archive-url = https://web.archive.org/web/20060928030713/http://www.thebulletin.org/article_nn.php?art_ofn=jf03norris | url-status = dead )).
* ((Citation | url = http://www.glennsmuseum.com/controller/controller.html | title = B61 Nuclear Bomb Preflight Controller Unit | publisher = Glenn’s museum)).

((United States nuclear devices))
((USAF equipment))

[[Category:Nuclear bombs of the United States]]
[[Category:Tactical nuclear weapons]]
[[Category:Military equipment introduced in the 1960s]]

Pages transcluded onto the current version of this page (help):

B61 nuclear bomb (edit)
Template:Abbr (view source) (protected)
Template:As of (view source) (template editor protected)
Template:Category handler (view source) (protected)
Template:Citation (view source) (protected)
Template:Citation needed (view source) (protected)
Template:Cite AV media (view source) (template editor protected)
Template:Cite book (view source) (protected)
Template:Cite journal (view source) (protected)
Template:Cite news (view source) (protected)
Template:Cite report (view source) (template editor protected)
Template:Cite web (view source) (protected)
Template:Clear (view source) (protected)
Template:Commons category-inline (view source) (template editor protected)
Template:Commonscatinline (view source) (template editor protected)
Template:Convert (view source) (template editor protected)
Template:Cvt (view source) (template editor protected)
Template:DMCA (view source) (template editor protected)
Template:Dated maintenance category (view source) (template editor protected)
Template:Dated maintenance category (articles) (view source) (template editor protected)
Template:Delink (view source) (protected)
Template:FULLROOTPAGENAME (view source) (template editor protected)
Template:Fix (view source) (protected)
Template:Fix/category (view source) (protected)
Template:Harvid (view source) (template editor protected)
Template:Has short description (view source) (template editor protected)
Template:Hlist/styles.css (view source) (protected)
Template:If empty (view source) (protected)
Template:Infobox (view source) (template editor protected)
Template:Infobox weapon (view source) (template editor protected)
Template:Main other (view source) (protected)
Template:Military navigation (view source) (template editor protected)
Template:Navbox (view source) (template editor protected)
Template:Nbsp (view source) (protected)
Template:Ns has subpages (view source) (protected)
Template:Pagetype (view source) (protected)
Template:Plain text (view source) (template editor protected)
Template:Reflist (view source) (protected)
Template:Reflist/styles.css (view source) (protected)
Template:SDcat (view source) (protected)
Template:Sfn (view source) (template editor protected)
Template:SfnRef (view source) (template editor protected)
Template:Short description (view source) (protected)
Template:Short description/lowercasecheck (view source) (protected)
Template:Sister-inline (view source) (template editor protected)
Template:Spaces (view source) (protected)
Template:Template other (view source) (protected)
Template:USAF equipment (edit)
Template:United States nuclear devices (edit)
Template:Use American English (view source) (template editor protected)
Template:WPMILHIST Infobox style (view source) (template editor protected)
Template:Webarchive (view source) (template editor protected)
Template:Which (view source) (template editor protected)
Template:Which? (view source) (semi-protected)
Template:Who (view source) (template editor protected)
Template:Who? (view source) (semi-protected)
Template:Yesno (view source) (protected)
Module:Arguments (view source) (protected)
Module:Category handler (view source) (protected)
Module:Category handler/blacklist (view source) (protected)
Module:Category handler/config (view source) (protected)
Module:Category handler/data (view source) (protected)
Module:Category handler/shared (view source) (protected)
Module:Check for unknown parameters (view source) (protected)
Module:Citation/CS1 (view source) (protected)
Module:Citation/CS1/COinS (view source) (protected)
Module:Citation/CS1/Configuration (view source) (protected)
Module:Citation/CS1/Date validation (view source) (protected)
Module:Citation/CS1/Identifiers (view source) (protected)
Module:Citation/CS1/Utilities (view source) (protected)
Module:Citation/CS1/Whitelist (view source) (protected)
Module:Citation/CS1/styles.css (view source) (protected)
Module:Commons link (view source) (template editor protected)
Module:Convert (view source) (template editor protected)
Module:Convert/data (view source) (template editor protected)
Module:Convert/text (view source) (template editor protected)
Module:Data (view source) (template editor protected)
Module:Delink (view source) (protected)
Module:Disambiguation/templates (view source) (protected)
Module:Footnotes (view source) (template editor protected)
Module:Footnotes/anchor id list (view source) (template editor protected)
Module:Footnotes/anchor id list/data (view source) (template editor protected)
Module:Footnotes/whitelist (view source) (template editor protected)
Module:GetParameters (view source) (template editor protected)
Module:If empty (view source) (protected)
Module:Infobox (view source) (template editor protected)
Module:Infobox/styles.css (view source) (template editor protected)
Module:InfoboxImage (view source) (template editor protected)
Module:Military navigation (view source) (template editor protected)
Module:Namespace detect/config (view source) (protected)
Module:Namespace detect/data (view source) (protected)
Module:Navbar (view source) (protected)
Module:Navbar/configuration (view source) (protected)
Module:Navbar/styles.css (view source) (protected)
Module:Navbox (view source) (template editor protected)
Module:Navbox/configuration (view source) (template editor protected)
Module:Navbox/styles.css (view source) (template editor protected)
Module:Ns has subpages (view source) (protected)
Module:Pagetype (view source) (protected)
Module:Pagetype/config (view source) (protected)
Module:Pagetype/disambiguation (view source) (protected)
Module:Pagetype/setindex (view source) (protected)
Module:Pagetype/softredirect (view source) (protected)
Module:Plain text (view source) (template editor protected)
Module:SDcat (view source) (protected)
Module:String (view source) (protected)
Module:String2 (view source) (template editor protected)
Module:Unsubst (view source) (protected)
Module:WPMILHIST Infobox style (view source) (template editor protected)
Module:Webarchive (view source) (template editor protected)
Module:Webarchive/data (view source) (template editor protected)
Module:Wikitext Parsing (view source) (protected)
Module:Yesno (view source) (protected)

Return to B61 nuclear bomb.

Retrieved from "https://en.wikipedia.org/wiki/B61_nuclear_bomb"