The B61 nuclear bomb is one of the primary thermonuclear weapons in the U.S. Enduring Stockpile following the end of the Cold War. It is an intermediate-yield strategic and tactical nuclear weapon featuring a two-stage radiation implosion design.The B61 is a variable yield bomb (0.3 to 340 kiloton yield in various versions and settings) designed for carriage by high-speed aircraft. It has a streamlined casing capable of withstanding supersonic flight speeds.