The U.S. National Nuclear Security Administration has announced the completion of the upgrade program of the new B61-12 nuclear weapons, and the impending start of manufacturing for the B61-13 variant.
The U.S. National Nuclear Security Administration (NNSA) has just announced, seventeen years after starting the design process, that production of the most recent American tactical nuclear weapon, the B61-12, has been completed. The Last Production Unit (LPU) of the B61-12 Life Extension Program (LEP) was completed on Dec. 18, 2024, said the agency, about three years after the beginning of the production and a total expense of around $9 billion.
The B61-12 LEP production
Although the B61-12 LPU was completed on Dec. 18, 2024, the announcement only arrived on Jan. 7, 2025. Earlier in 2024, the NNSA also disclosed the completion of the production of the trainers used to certify Air Force personnel and bases prior to delivery of the actual weapon systems.
Trainers give Airmen the essential ability to familiarize themselves with loading the weapon on delivery platforms, as well as maintaining the weapon, said the agency. The program produced 3 different Type 3 Trainer versions with a total build of more than 100 military training weapons.
The First Production Unit (FPU) of the B61-12 was delivered in 2021, with full-rate production starting a year later. The NNSA also mentioned in earlier reports that the LEP was expected to complete production and close out in FY2026.
“Completing the B61-12 on schedule is the latest example of what we’ve been saying for several years now: NNSA is delivering capabilities at the pace and scale needed by our Department of Defense partners and our deterrence requirements,” NNSA Administrator Jill Hruby said in the announcement.
The program allows to continue to assure the safety, security, and effectiveness of the weapon, as well as consolidated and replaced the -3, -4, -7, and -10 B61 variants. “The B61-12 LEP, which is critical to sustaining the Nation’s air delivered nuclear deterrent capability, extends the service life by at least 20 years through refurbishing, reusing, or replacing all the bomb’s nuclear and non-nuclear components,” added the agency.
It is important to remember that the B61-12 is not a “new” weapon in the strict sense of the word, as it takes the warheads from the older bombs and puts them in the new body, thus leaving the same number of weapons in the nuclear stockpiles. The NNSA says there is no overall change in military characteristics of the weapon, as it balances greater accuracy provided by the modern tail kit assembly with a substantial reduction in yield.
The total program cost of the B61-12 is around $9 billion, with each warhead accordingly having a price of about $22.5 million if we consider the initial plan to manufacture 400 weapons.
The B61-13
With production of the B61-12 LEP now complete, the NNSA is now transitioning to the production of the B61-13 bomb. According to an October 2024 report from the National Nuclear Security Administration, the First Production Unit (FPU) of the B61-13 is scheduled for FY 2026, while the completion of the works is planned for FY2028. The development of the new variant was first announced in 2023.
“The B61-13 will strengthen deterrence of adversaries and assurance of allies and partners by providing the President with additional options against certain harder and large-area military targets”, said the press statement at the time. Similarly to the B61-12, the number of the nuclear bombs in the inventory will not change, as the B61-13 will replace some of the B61-7s in the current stockpile and the number of B61-12s to be produced will be lowered by the same amount as the number of B61-13s produced.
The B61-13 will have a yield similar to the B61-7 (reportedly 340-360 kt), reusing its warhead, and will include the modern safety, security, and accuracy features of the B61-12. The NNSA mentioned that, in the near term, the B61-13 fulfills the Nuclear Posture Review commitment to leverage available nuclear and non-nuclear capabilities while DoD implements its new strategy for defeat of hard and deeply buried targets.
The B61-13 will be carried by the incoming B-21 Raider, but it is not yet planned to be carried by the F-35 fleet.
The B61-12
A variable yield design, with reported yields between 0.3 and 340 kilotons, the B61 is an air-delivered family of tactical nuclear weapons developed by the USA since December 1962 in 14 iterations. The B61-0, the first version, started production in 1967, and since then around 3,155 B61 bombs have been produced, with an estimated 540 in service and 415 in reserve in 2012.
Around 400 B61-12 were then planned, converted from previous B61-4 (a version that started production in 1979) and using components from older warheads, to serve alongside the around 50 B61-11 bunker buster nuclear weapons. The weapon was planned to become the only remaining gravity delivered nuke in the inventory, at least until the B61-13 was announced.
Originally an unguided weapon, the basic B61 had a streamlined casing 11 feet and 8 inches long (3.56m) and a diameter of 13 inches (33 cm) able to withstand supersonic flight. Weighting around 700 pounds (just over 300 kg), the B61 was designed to be carried by tactical airplanes of the United States Air Force and of NATO partner nations, thanks to the NATO Nuclear Weapons Sharing Program.
The upgraded weapon carries a low-yield nuclear warhead with four yield options and is delivered in either ballistic or guided-gravity drop modes, thanks to a new Boeing-built tail assembly that includes an Inertial Navigation System (INS) precision-guidance package and two spin rocket motors.
The guided tail-kit assembly allows both improving the accuracy and gifting the B61 with some standoff range. Reportedly, the B61-11 has an accuracy of 110-170 meters, while the guided B61-12 cuts it down to only 30 meters, making it possible to use a lower-yield warhead.
The U.S. Air Force certified its B-1 Lancer, B-2 Spirit, B-52 Stratofortress, F-16 Fighting Falcon and F-15E Strike Eagle to carry the original B61, along with the Navy F/A-18 Hornet and the since retired A-6 Intruder, A-4 Skyhawk, and F-111. The F-16s, as well as while the German and Italian Panavia Tornado, are also certified to carry the B61 for various NATO partner nations.
In 2020, the F-15E Strike Eagle became the first aircraft certified to carry the B61-12, later followed by the F-35A Lightning II and then by the B-2 Spirit, the F-16 Fighting Falcon and the German Air Force Panavia Tornado. According to NNSA, work is underway to integrate the B61-12 on the Italian Air Force’s Panavia Tornado and the U.S. Air Force’s incoming B-21 stealth bomber.
