Though some in the U.S. government feel Russia will rely increasingly on non-conventional and nuclear arms, including tactical nuclear weapons, that does not make a case for continuing development of a low-yield, sea-launched nuclear cruise missile, a Pentagon official said here Wednesday.

The sea-launched nuclear cruise missile (SLCM-N), with its W80-4 variant warhead, “was not necessary and nothing has changed,” Colin Kahl, undersecretary of defense for policy, said Wednesday at the 2022 Defense News Conference.

To support his case, Kahl repeated some arguments the Biden administration made this spring, when SLCM-N and the W80-4 vanished from federal budget requests: the sea-launched missile would be too expensive, arrive too late to be useful to the Navy and take up development funding better used on conventional and cyber programs.

Kahl also said the U.S. planned to maintain an inventory of tactical nuclear weapons including the B61-12 gravity bomb, which eventually will fly aboard the new B-21 long-range bomber, and “a sea-launched ballistic missile that has a lower-yield on it.”

The latter is the W76-2 that went to sea around December 2019. Arms control advocates who supported Biden’s candidacy had largely opposed W76-2 on the grounds that it might encourage limited nuclear exchanges. 

Proponents said the weapon was a good, relatively cheap, way to prevent Russia, which has many more lower-yield nuclear weapons than the United States, from initiating a limited nuclear strike.

The Biden administration’s unpublished nuclear posture review — Congress got a classified version to read over the summer — proposed eliminating SLCM-N W80-4 and discontinuing maintenance of the megaton-class B83 gravity bomb.

Congress ignored that proposal and produced a series of defense authorization and appropriations bills that could, depending on how House and Senate proposals are reconciled, allow both SLCM-N and B83 to continue without interruption. 

Kahl said it might be a matter of weeks before the unclassified national defense strategy, which includes the nuclear posture review, is published in an unclassified form.

Kahl also said that China, with its “breathtaking expansion of their nuclear arsenal,” would dictate the size of future investments in the U.S. nuclear arsenal, not Russia.

Citing cultural and historic ties to some people living within Ukraine’s borders, Russia invaded Ukraine in February for the second time in a less than a decade. With the war still grinding on, Kahl said that “some” have assessed that Moscow’s conventional armed forces are far less capable than believed before the invasion.