US Navy ballistic missile submarines — boomers — are now sailing with ballistic missiles armed with new "low-yield" nuclear weapons, the Department of Defense announced Tuesday.


"The U.S. Navy has fielded the W76-2 low-yield submarine-launched ballistic missile (SLBM) warhead," John Rood, under secretary of defense for policy, said in a statement.

"This supplemental capability strengthens deterrence and provides the United States a prompt, more survivable low-yield strategic weapon," he said.

Rood, who told the Associated Press that these new weapons lower the risk of nuclear war, added that it "demonstrates to potential adversaries that there is no advantage to limited nuclear employment because the United States can credibly and decisively respond to any threat scenario."

The fielding of the new low-yield nuclear warheads, which arm submarine-launched Trident II missiles, was first reported by the Federation of American Scientists, which explained that each W76-2 has an explosive yield of about five kilotons, significantly smaller than the 90-kiloton W76-1 or the larger, 455-kiloton W88.

For comparison, the W76-2 has a smaller explosive yield than either of the atomic bombs dropped on Hiroshima and Nagasaki — which together killed hundreds of thousands of people.

It is unclear exactly when and on which vessels the new "low-yield" nuclear weapons were deployed, but FAS, citing unnamed sources, reports the new weapons may have been deployed aboard the US Navy Ohio-class ballistic missile submarine (SSBN) USS Tennessee, which set out on an Atlantic deployment at the end of last year.

The W76-2 is a product of the 2018 Nuclear Posture Review.

"DoD and National Nuclear Security Administration (NNSA) will develop for deployment a low-yield SLBM warhead to ensure a prompt response option that is able to penetrate adversary defenses," the review explained.

"This is a comparatively low-cost and near term modification to an existing capability that will help counter any mistaken perception of an exploitable 'gap' in U.S. regional deterrence capabilities."

Production of the new warheads began in January 2019 at the Pantax Plant in Texas.

While the Department of Defense argues in favor of the new weapons, many arms control experts argue that low-yield nuclear weapons lowers the barrier to entry into nuclear-armed conflict, thus increasing the risk of a conflict escalating to a full-scale nuclear war.

This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.