US to construct B61-13 nuclear gravity bombs

An F-35A Lightning II drops a mock B61-12 at Sandia National Laboratories' Tonopah Test Range in November 2020. The new B61-13 will augment the B61-12. (Sandia National Laboratories)

The US Department of Defense (DoD) announced that it would construct a new type of nuclear gravity bomb, designated B61-13, to complement B61-12 production.

The new bombs are intended to replace some of the B61-7 stockpile while retaining a similar nuclear yield, according to a 27 October announcement. Although production of a new bomb is ongoing, designated the B61-12, the B61-13s are to have a larger yield and provide “additional options against certain harder and large-area military targets”, according to the announcement.

The B61-7 yield can be up to 360 Kt, according to previous Janes reporting, while the B61-12 is capable of yields of up to 340 Kt.

Production of the new bombs is not intended to increase the US's total nuclear stockpile. Instead, production of the new bombs is to come at the expense of B61-12 production, according to the department. As of 2020 Janes assessed that approximately 480 B61-12s were to be produced under the Life Extension Programme (LEP), intended to replace previous B61 variants. The first B61-12 was delivered to the DoD in 2021.

Although the DoD release stated that the new bomb was not conceived of in response to a specific current event, it quotes Assistant Secretary of Defense for Space Policy John Plumb as saying that it is “reflective of a changing security environment and growing threats from potential adversaries”.