OVERVIEW: A U.S. variable-yield tactical and strategic thermonuclear bomb developed during the Cold War. The B61 is air-delivered and remains in service with modifications to support both gravity drop and precision-guided delivery.

DETAIL: The B61 is a low- to intermediate-yield two-stage thermonuclear weapon, developed for flexibility across a wide range of delivery aircraft and missions. Designed with a selectable yield system, the B61 includes various operational configurations (mods), enabling both tactical and strategic deployment. It is compact, with a narrow fuselage and streamlined nose, allowing high-speed carriage. Safety features include permissive action links and enhanced electrical fuzing to prevent unauthorized use or accidental detonation.

The B61 Mod 3, 4, 7, and 10 were deployed primarily during the 1970s–90s, with yields ranging from 0.3 to 340 kilotons. The Mod 7 served strategic roles, while Mods 3 and 4 supported tactical missions. The Mod 11 was introduced as a ground-penetrating bunker buster. The current Mod 12 adds a tail guidance kit for improved accuracy and low-yield options for limited nuclear strike scenarios.

B61 bombs are integrated with aircraft through special suspension units and arming wires, and typically employed via laydown, toss, or free-fall methods. Intended use includes suppression of enemy air defenses, deep strike, and deterrence against hardened or high-value targets.

SPECIFICATION:
Weight: ~700 lb (320 kg)
Length: ~141 in (3.58 m)
Diameter: ~13.3 in (340 mm)
Yield: 0.3 to 340 kilotons (variable, depending on mod)
Guidance: None (Mods 0–11), Tail guidance kit (Mod 12)
Fuse: Airburst, contact, or delayed options

PERFORMANCE:
Range: Aircraft-dependent
Delivery Altitude: Low to high altitude
Deployment Modes: Free-fall, laydown, or guided (Mod 12)
Accuracy: Ballistic (Mods 0–11), CEP <30 m (Mod 12)

NOTE:
IOC: ~1968 (initial Mod), 2020s (Mod 12)
Operators: United States
Platform: B-2A Spirit, F-15E Strike Eagle, F-16C/D Fighting Falcon, F/A-18 Hornet, PA-200 Tornado, F-35A Lightning II, B-21 Raider (future)
Conflicts: Cold War (deployed, not used), ongoing deterrent role

SOURCE:
U.S. Department of Defense: https://www.defense.gov/
U.S. Department of Energy: https://www.energy.gov/
Federation of American Scientists (FAS): https://fas.org/nuke/guide/usa/bomb/b61.htm
National Nuclear Security Administration (NNSA): https://www.energy.gov/nnsa/b61-12-life-extension-program