The Tsetse was a small American nuclear bomb developed in the 1950s that was used as the primary in several US thermonuclear bombs and as a small stand-alone weapon of its own.

The Tsetse had a boosted composite core which used 2.25 kg Pu-239, 1.4kg U-235 and 6g tritium.^[1] The nominal yield was 10 kilotons. The design was shared with the UK where the anglicised version was known as Tony.^[2] The difference between Tsetse and Tony was in the high explosives used. The UK considered the PBX 9404 too shock sensitive and replaced it by EDC-11. This reduced the nominal yield to 8.5 kilotons.^[3]

The Tsetse primary was used in the US B43 nuclear bomb, W44 nuclear warhead, W50 nuclear warhead, B57 nuclear bomb, and W59 nuclear warhead, according to researcher Chuck Hansen.^[4]

After deployment of the B43 two problems were identified in the primary. In 1961 Los Alamos scientists concluded that the primary was not one point safe under all conditions. A long series of tests was needed to develop a safe version. The second problem was related to tritium aging. To investigate a lifetime extension of the B43 an aged B43 was fired. The test resulted in half the yield. This was quite a shock as it affected not only the B43 but all similar weapons.^[5][6] The solution was to more frequently replenish the tritium supply.^[6] This problem was apparently shared by the Python primary designs.

Characteristics of these weapons are:

Based on this information it can be assumed that the Tsetse design itself corresponds to the size of the W44 warhead, 349-millimetre (13.75 in) diameter and 640-millimetre (25.3 in) long, with a weight of around 77 kilograms (170 lb).