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Korean DMZ Conflict
Part of Division of Korea

American and South Korean soldiers on the DMZ, August 26, 1967.
DateOctober 1966  – October 1969
Result Undetermined
United States United States
South Korea Republic of Korea (Third Republic)
North Korea Democratic People's Republic of Korea
Commanders and leaders
United States Charles H. Bonesteel III
South Korea Park Chung-hee
North Korea Kim Il-sung
Casualties and losses
United States:
43 killed
111 wounded
Republic of Korea:
299 killed
550 wounded[1]
397 killed
12 soldiers and 2,462 agents captured[2]

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The Korean DMZ Conflict, also referred to as a Second Korean War[citation needed], was a series of low-level armed clashes between North Korean forces and the forces of South Korea and the United States, largely occurring between 1966 and 1969; although other incidents between the two Koreas occurred thereafter.[3]


The Korean War had devastated both North and South Korea and while neither side renounced its claims to reunify Korea under their control neither side was in a position to force reunification.

In North Korea the departure of the People's Liberation Army in October 1958 allowed Kim Il-Sung to consolidate his power base and embark on the Chollima Movement of collectivised agriculture and industrialization to build a base for reunifying Korea by force. North Korea remained dependent on the Soviet Union for technology and on China for agricultural assistance. The Sino–Soviet split led to the Soviets suspending aid to North Korea in December 1962 saying that the DPRK was leaning too much towards China[4].

In South Korea, economic aid from the United States and other western nations allowed the South to rebuild rapidly, achieving 5.5% annual growth by the mid-1950s. The April Revolution that forced President Syngman Rhee from office in April 1960 was followed by a brief period of democracy before a coup d'état led by General Park Chung-hee seized power in May 1961. Despite the political turmoil the South Korean economy continued to grow, led by the industrial sector[4].

By 1962 the population and economy of South Korea was almost twice that of North Korea. Kim Il-Sung apparently recognised that the growing economic strength of the South would only increase over time and would give the South the ability to force reunification on its terms, but also the economic boom and the autocratic nature of the Park administration had given rise to widespread dissent. Without Soviet support a conventional attack on the South was impossible and so Kim saw a possibility to achieve reunification through unconventional warfare. On 10 December 1962 Kim proposed a new military strategy to the Central Committee of the Workers' Party of Korea, with increased emphasis placed on irregular warfare, agitation and propaganda, to be achieved by the end of the current Seven-Year Plan in 1967[4].

In June 1965 President Park signed a treaty normalizing relations with Japan which included payment of reparations and the making of soft-loans from Japan and led to increased trade and investment between South Korea and Japan. In July 1966 South Korea and the United States signed a Status of Forces Agreement establishing a more equal relationship between the two countries. With its growing economic strength and the security guarantee of the United States, the threat of a conventional invasion from the North seemed increasingly remote[4]. Following the escalation of the Vietnam War with the deployment of ground combat troops in March 1965, South Korea sent the Capital Division and the 2nd Marine Brigade to South Vietnam in September 1965, followed by the White Horse Division in September 1966.

The start of the hostilities can be traced to a speech given by North Korean leader Kim Il-sung on October 5, 1966, at the Workers' Party of Korea Conference where the status quo of the 1953 Armistice Agreement was challenged. Kim Il-Sung apparently perceived that the division of effort by the South Korean military and the ever-growing escalation of the US commitment in Vietnam created an environment where irregular warfare could succeed in a way conventional warfare could not[4]. Kim believed that he could force a split between the U.S. and South Korea through armed provocations targeting U.S. forces that, together with other worldwide commitments and small wars, would force the U.S. to reassess or relinquish its commitment to South Korea, allowing North Korea to incite an insurgency in the South that would topple the Park administration[5].

North Korean forces

In 1966 the Korean People's Army (KPA) deployed eight infantry divisions along the DMZ, backed by eight more infantry divisions, three motorized infantry divisions, a tank division and a collection of separate infantry and tank brigades and regiments. While strong, this conventional force did not possess a significant advantage over the South, and it was unlikely that the North could deliver a knockout blow before the U.S. could deploy additional forces[6].

The main unconventional warfare arm was the Reconnaissance Bureau of the Ministry of Defense under the operational control of the Liaison Department of the Worker's Party of Korea which included the 17th Foot Reconnaissance Brigade and the all-officer Unit 124 and 283rd Army Units. These units were all highly trained and indoctrinated, skilled in demolitions and small-unit tactics, they would usually operate in small teams of 2-12 men, lightly-armed with either PPS submachine guns or AK-47s. The Reconnaissance Bureau also controlled the 23d Amphibious Brigade, which used specially made infiltration boats to operate along the South Korean coastline. The Reconnaissance Bureau could also use conventional KPA and Korean People's Navy forces to support the infiltration and exfiltration of its teams[6].

In addition to the offensive irregular forces, North Korea also deployed several thousand operator-agitators to select, train, and supervise informants and guerrilla recruits, while others attempted to cause individual defections and unit dissatisfaction in the ROK military and generally undermine the morale of both the ROKs and the Americans[6].

United States and Republic of Korea forces

The major U.S. ground combat units in Korea were the 2nd Infantry Division (2ID) and 7th Infantry Division (7ID), I Corps and 8th Army. 2ID stood with the 3rd Brigade manning 29.8 km of the Korean Demilitarized Zone (DMZ) essentially due north of Seoul on either side of Panmunjom, with another nine Republic of Korea Army (ROKA) Divisions manning the remaining 212.8 km of the DMZ. All U.S. and ROKA forces were under the unified operational control of United Nations Command (Korea) (who was also the commander United States Forces Korea), General Charles H. Bonesteel III.[7] Both U.S. Army Divisions were seriously under strength as Vietnam had priority for manpower and equipment. Troops were equipped with M14 rifles rather than M16s, the only available tanks were older gasoline powered M48A2Cs, and there were a total of only 5 UH-1 Huey helicopters in South Korea seriously restricting the ability to hunt and engage infiltrators. Troops were generally draftees serving a 13 month tour, while experienced officers and NCOs preferred service in Vietnam to Korea[7]. The ROK Divisions were well trained and highly motivated with many of the officers and NCOs veterans of the Korean War, but all their equipment dated back to that war; their standard rifle was still the M1 Garand[7].

The main operational objective of the US and ROK Divisions was to defend against a conventional invasion from North Korea in a repeat of the attack of June 1950. While there were regular infiltrations into the South for intelligence-gathering, unconventional warfare was not seen as a particular threat and the troops were not generally trained or equipped for this role[8]. No counter-guerilla units or village militias existed in South Korea in 1966 and infiltrators were variously hunted by the ROK Army, Police and the Korean Central Intelligence Agency with no unified control[7].

The ground forces were supported by fighter-bombers of the USAF 314th Air Division and by the Republic of Korea Air Force. The seas around Korea were under the control of the United States Seventh Fleet and the Republic of Korea Navy. As with the Army, the war in Vietnam was the main focus of the USAF and the USN in the Pacific[7].

Defense Strategy

Following the first attack on US forces in November 1966, General Bonesteel formed a working group to analyse the North Korean strategy and develop a counter-strategy to defeat it. Finding the existing U.S. Army tactical doctrines to be inapplicable to the situation they were facing, the working group developed its own doctrine to meet its operational needs. Three types of operations were identified: first to guard against infiltration across the DMZ; second was a similar naval effort along the coasts; and third was counterguerrilla operations in the interior. All three types of operations had to be accomplished without jeopardizing the conventional defense of South Korea or escalating the conflict from low-intensity to a full war[9].

Defending the DMZ

Starting in 1967 the UN Command developed a layered defense of the DMZ. The Armistice restricted fortification within the DMZ, where defences were limited to patrols and observation posts without heavy weapons. More aggressive patrolling of the DMZ was ordered with patrols going out for twenty-four hours, reconnoitering by day and establishing ambushes at night, most U.S. casualties occurred during these patrols. The observation posts were fortified with sandbags and machine-guns and recoilless rifles were frequently kept hidden there in breach of the Armistice. General Bonesteel obtained $30m in funding from the U.S. Army Combat Developments Command to create a DMZ test Barrier along the portion of the DMZ occupied by the 2ID and the ROKA 21st Infantry Division. Beyond the southern boundary or "south tape" of the DMZ, no defensive restrictions applied and a combined U.S.-Korean engineer force constructed an in-depth Barrier comprising a 3m tall chain-link fence, topped by triple strands of concertina wire and reinforced by interwoven saplings and steel engineer pickets, behind it a narrow, raked-sand path paralleled the fence to highlight footprints. Behind the sand strip was a 120m wide cleared kill-zone in which mines and tanglefoot wire fronted a line of conventional defensive positions of interlocking machine guns and pre-registered mortar and artillery fire dominate the kill zone. Observation towers stood at intervals along the trace to permit clear view of the open areas. Various electronics and sensors were tested on the Barrier similar to the McNamara Line in Vietnam, but with the exception of Starlight scopes they were largely ineffective. The Barrier could not prevent infiltration (it was estimated that the North Koreans could cut through the fence in 30-40 seconds), rather it was intended to slow movement and provide easy observation. Behind the Barrier were the quick-reaction forces of mechanized infantry, tanks and armored cavalry who would hunt down infiltrators. The rules of engagement were also loosened to allow the frontline troops to use artillery and mortar fire against known KPA elements in or south of the DMZ and against KPA firing from north of the Military Demarcation Line, although in practice this was only used sparingly. A new 4 monthly rotation scheme was introduced in October 1967 to ensure that each Battalion received only its fair share of time manning and patrolling the Barrier. 7ID sent one infantry battalion at a time to augment the 3rd Brigade, 2ID, this increased the defense to four Battalions on the line plus the quick-reaction forces.[10].

Defending the Coastline

Preventing infiltration at sea created an impossible challenge for the UN Command, which lacked suitable aircraft, ships, radar and communications. The ROK Navy possessed only 72 vessels to patrol over 7000km of rugged coastline. Along the coasts some 20,000 unarmed coastwatchers, sometimes supplemented by ROKA reservists patrolled the beaches and when signs of landings were discovered these would be reported to the National Police and quick reaction forces would be deployed. Poor communications and a lack of helicopters meant that the quick reaction forces seldom arrived in time before the infiltrators dispersed in the Korean hinterland[10].

Counterinsurgency operations

During 1966 and into 1967, there was no coordinated counterinsurgency plan in South Korea. Infiltrations were dealt with on an ad hoc basis by the ROKA, National Police, Army counter-intelligence units and the KCIA usually depending on the estimate of the threat and whichever units happened to be nearby. President Park was reluctant to raise and arm a civilian militia as he did not fully trust the loyalty of the populace to his government.

General Bonesteel regarded counterinsurgency as entirely an internal responsibility for the South Korean Government and while he provided some material support including his helicopters and several Special Forces A-Teams from the 1st Special Forces Group on Okinawa to train the ROKA and the newly formed Combat Police in counterinsurgency tactics, he declined to take responsibility for counterinsurgency operations.

By late 1967 it was clear that the North Koreans were attempting to develop a full scale insurgency in the South with strongholds in the Taebaek Mountains and around Jirisan mountain. President Park, in consultation with General Bonesteel, developed a counterinsurgency strategy in the form of Presidential Instruction #18. The instruction established a national coordinating council with clear chains of command for all classes of incidents ranging from individual agent sightings to province-level unrest. Eight (later ten) new ROKA counter-infiltration battalions were to be formed, together with further expansion of the Combat Police[11].

The Blue House Raid and the Pueblo Incident

On the night of 17 January 1968, 31 men of Unit 124 penetrated the 2ID sector of the DMZ by cutting through the chain-link fence and passing undetected within 30m of a manned 2ID position. The mission of Unit 124, as explained to them by KPA Reconnaissance Bureau chief, Lieutenant General Kim Chung-tae, was "to go to Seoul and cut off the head of Park Chung Hee". It was believed that by assasinating Park the South would be thrown into turmoil and the people would rise up and fight the government and the US imperialists leading to reunification. On the afternoon of 19 January Unit 124 encountered 4 woodcutters, but rather than killing them the Unit 124 commander proceeded to try to indoctrinate them with details of the coming insurrection and the glories of North Korean communism. The North Koreans released the woodcutters with warnings not to notify the authorities. The woodcutters notified the Police as soon as possible and an alert went up the chain of command in accordance with Presidential Instruction #18. By the morning of 20 January the police and military were on full alert, but not knowing the mission of Unit 124 they were attempting to guard important sites as well as the approaches to Seoul. Unit 124 entered Seoul in 2-3 man cells on 20 January and noting the heightened security and by eavesdropping of ROKA radio frequencies they devised a new assault plan, changing into uniforms of the 26th Infantry Division they proceeded to march the last 2km to the Blue House, posing as a unit returning from a counter-guerilla patrol. After passing several ROKA and Police units, Unit 124 was stopped by a Police unit only 800m from the Blue House. The Police began questioning the Unit 124 members and when a Police officer grew suspicious and drew his pistol he was shot by a Unit 124 member, a running gun battle developed in which 2 members of Unit 124 were killed. The ROKA, Police and U.S. Army began a massive manhunt as the remaining members of Unit 124 attempted to escape north and cross the DMZ. A further 26 members of Unit 124 were killed, one captured and two missing presumed killed (though at least one member of the Unit apparently survived and returned to North Korea[12]) while 68 South Koreans and 3 U.S. Army servicemen were killed[13]

Scale of conflict

From October 1964 the North Koreans increased the infiltration of intelligence-gatherers and propagandists into the South. By October 1966 more than 30 South Korean soldiers and at least 10 civilians had been killed in clashes with North Korean infiltrators, however no similar clashes had taken place along the U.S. controlled section of the DMZ. In October 1966 the South Koreans staged a retaliatory attack against without seeking the approval of General Bonesteel, this caused tension between the U.S. command which wished to avoid violations of the Armistice and the South Koreans who were suffering ongoing losses[14].

South Korea launched at least three retaliatory cross-border raids in late 1967 using small teams of North Korean defectors. The raids killed 33 KPA soldiers[15].

The hostilities were such that on April 1, 1968, the Department of Defense on the recommendation of General Bonesteel declared the DMZ-Imjin River area as a hostile fire zone, entitling service members stationed in the area to hostile-fire pay and later for the award of the Combat Infantryman Badge and Combat Medical Badge to all qualified men serving north of the Imjin River[16].






See also: Division of Korea § Post Korean War infiltrations, incursions and incidents


  1. ^ Bolger, Daniel (1991). Scenes from an Unfinished War: Low intensity conflict in Korea 1966-1969. Diane Publishing Co. p. Table 3. ISBN 978-0788112089.
  2. ^ Bolger, Table 3
  3. ^
  4. ^ a b c d e Bolger, Chapter 1 Background
  5. ^ Bolger, Chapter 2 A Call to Arms
  6. ^ a b c Bolger, Chapter 1 Enemy
  7. ^ a b c d e Bolger, Chapter 1 Troops Available
  8. ^ Bolger, Chapter 1 Mission
  9. ^ Bolger, Chapter 2 The Doctrinal Void
  10. ^ a b Bolger, Chapter 2 Anti-Infiltration: The Sea Approaches
  11. ^ Bolger, Chapter 2 Counterinsurgency: The Interior
  12. ^ "A would-be assassin builds a new life". JoongAng Daily. 4 November 2009.
  13. ^ Bolger, Chapter 3 The Blue House Raid
  14. ^ Bolger, Chapter 2
  15. ^ Lee Tae-hoon (7 February 2011). "S. Korea raided North with captured agents in 1967". The Korea Times.
  16. ^ Bolger, Chapter 2 The Conventional Response: Resources
  17. ^ Bolger, Chapter 2 First Blood
  18. ^ Bolger, Chapter 3
  19. ^ Bolger, Chapter 3 The Ulchin-Samchok Landings
  20. ^ Bolger, Chapter 4 The North Strikes Back
  21. ^ Bolger, Appendix 4