US expands nuclear arsenal: B61-13 warhead boasts 360-kiloton yield

The United States has officially commenced the modernization of its B61 nuclear warheads, transitioning to the advanced B61-13 variant, according to an announcement by the National Nuclear Security Administration (NNSA).

The B61-13 warhead is designed with a yield of 360 kilotons, significantly increasing its destructive power compared to the preceding B61-12 model, Caliber.Az reports referring to foreign media.

The modernization efforts are taking place at the Y-12 National Security Complex in Oak Ridge, Tennessee, where modifications to the existing arsenal are currently underway.

According to the NNSA, the new B61-13 variant represents “a more powerful version of the B61-12, providing the US president with additional capabilities to target more complex and fortified military installations.”

The B61-12 warheads, which replaced earlier versions (B61-3, B61-4, B61-7, and B61-10), feature yields ranging between 0.3 and 50 kilotons. While these had lower explosive power, their advanced tail guidance system made them more precise. This system allows for high-altitude deployment without the need for a parachute, enabling the bomb to autonomously glide toward its target over long distances and adjust its trajectory as needed.

The US Department of Defence received its final batch of B61-12 warheads in December 2024, following updates at the Y-12 National Security Complex. The Federation of American Scientists (FAS) reports that the United States is preparing to deploy these modernized warheads to NATO airbases in Europe.

As of 2023, approximately 100 older B61-3 and B61-4 tactical nuclear bombs were stored in underground facilities across NATO airbases in Europe. These include:

• Büchel Air Base (Germany) – 15 bombs

• Kleine-Brogel Air Base (Belgium) – 15 bombs

• Volkel Air Base (Netherlands) – 15 bombs

• Ghedi Air Base (Italy) – 15 bombs

• Aviano Air Base (Italy) – 20 bombs

• Incirlik Air Base (Türkiye) – 20 bombs

These bombs can be carried and deployed by NATO aircraft, including the F-35A, F-15E, F-16, and Tornado tactical fighter-bombers. However, the primary stockpile of B61 nuclear weapons remains within the continental United States.

The US is also reconstructing underground storage facilities at Lakenheath Air Base in the United Kingdom, a location previously used to house nuclear bombs before their removal in 2008. A report by the Federation of American Scientists states that these facilities are being upgraded to WS3-type storage units, which are specifically designed to store nuclear weapons.

“As of February 2025, there is no confirmed public indication that nuclear weapons have been redeployed at the UK's Lakenheath Air Base,” the report states. “We believe the restoration of the nuclear mission at the airbase is primarily a contingency measure rather than an active deployment.”

The US government allocated funding for these upgrades in fiscal year 2023, using the term “special weapons” to refer to nuclear munitions in official documentation.

By Tamilla Hasanova