This is America’s latest nuclear bomb

13 nuclear bomb versions, Mod 0 through Mod 12, have been designed; nine of these entered production. Now, the DoD is pursuing a 14th.
Miguel Ortiz Avatar
(Los Alamos National Laboratory)

As of March 28, 2023, the Federation of American Scientists reports that the United States possesses a stockpile of 5,244 nuclear warheads, and 1,670 of these are deployed on ballistic missiles and gravity bombs. That’s right, America’s nuclear arsenal still includes traditional gravity bombs. The primary model in the stockpile is the B61 nuclear bomb. Designed in 1963 at the Los Alamos National Laboratory, production engineering of the B61 began two years later. Thirteen versions of the bomb, Mod 0 through Mod 12, have been designed; nine of these entered production. Now, the DoD is pursuing a 14th version of the B61.

Four B61s sit on a bomb rack.
Four B61s sit on a bomb rack (DoD photo)

On October 27, 2023, the DoD announced the pursuit of the B61-13 nuclear gravity bomb. Pending Congressional authorization and appropriation, the Mod 13 would be produced by the Department of Energy’s National Nuclear Security Administration. The decision to pursue the new bomb variant was made in response to “the demands of a rapidly evolving security environment as described in the 2022 Nuclear Posture Review,” as noted in a DoD press release.

An assembled (background) and disassembled (foreground) B61.
An assembled (background) and disassembled (foreground) B61 (DoE photo)

“Today’s announcement is reflective of a changing security environment and growing threats from potential adversaries,” Assistant Secretary of Defense for Space Policy John Plumb said in the DoD press release. “The United States has a responsibility to continue to assess and field the capabilities we need to credibly deter and, if necessary, respond to strategic attacks, and assure our allies.”

An F15-E carrying a B61 nuclear bomb Joint Test Assembly.
An F15-E carrying a B61 Joint Test Assembly (U.S. Air Force)

Deliverable by modern aircraft, the B61-13 would replace some of the B61-7s that are currently in service. Converted from Mod 1 variants of the B61, the Mod 7 reportedly has four yield settings including 10 and 340 kilotons. The DoD press release notes that Mod 13 would have a similar yield to the Mod 7. “While it provides us with additional flexibility, production of the B61-13 will not increase the overall number of weapons in our nuclear stockpile,” Plumb highlighted.

An inert B61 nuclear bomb used for training at Volkel Air Base.
An inert B61 used for training at Volkel Air Base in The Netherlands (U.S. Air Force)

The latest version of the B61, the Mod 12, entered full production in November 2021. Upon entering service, the modern B61-12 replaced some Mod 3, Mod 4, and Mod 7 bombs in America’s stockpile. The ground-penetrating Mod 11 remained fully in service. Taking advantage of the production capabilities used to manufacture the Mod 12, the Mod 13 would include the same modern safety, security, and accuracy features. The DoD notes that the decision to pursue the B61-13 is not in response to any specific current event.