America Built 3,155 B61 Nuclear Bombs. Around 50 Are Still in Turkey.

One of the longest-serving nuclear weapons in America's arsenal is the B61 nuclear free-fall bomb. The B61 bomb was first introduced in 1966 with more than three thousand bombs produced to date. The bomb is famous for its adjustable yield capability, giving it the versatility to operate in both the tactical and strategic nuclear roles. The United States forward deploys many of the bombs in Europe, with up to fifty bombs currently maintained at Incirlik Air Force Base in Turkey.

In 1960, Sandia National Laboratory and Los Alamos Scientific Laboratory began development of a new nuclear free-fall bomb. The bomb, nicknamed FUFO (full fuzing option), would be capable of adjusting its explosive yield to the mission, high-speed or low-speed delivery, high altitude or low altitude delivery, and airburst or contact burst fuzing capability. Each B61 is 11.8 feet long, 13 inches wide and weighs approximately 700 pounds. (The B61-11, an earth-penetrating version of the bomb, weighs an extra 450 pounds.)

The bomb has several deployment techniques depending on the nature of the target. These including free-fall airburst, a parachute-retarded airburst, a free-fall surface burst, or a "laydown" from a low-flying aircraft that involves the use of a kevlar drag parachute to quickly slow the bomb to safe impact speed. Free-fall airburst, for example, could be used by a strategic bomber against an undefended target. Low-altitude laydown could be utilized by tactical aircraft such as an F-16 Fighting Falcon flying a nuclear bombing mission against ground forces guarded by alert air defenses.

Between 1966 and 1997 the U.S. government built 3,155 B61 bombs of all types, both strategic and tactical. Most of these bombs are dismantled or inactive. A 2019 assessment by the Bulletin of the Atomic Scientists estimates the U.S. Air Force has 322 strategic nuclear bombs actively deployed, including the B83, B61-7 and B61-11 bombs. Exactly how many of these bombs are B61 is not clear, but the B83 with a 1.2 megaton yield is the largest thermonuclear bomb in the U.S. inventory and likely makes up a minority of the strategic bombs.