First U.S. Navy Sub Deploys With Tactical Nuclear Weapons

USS Tennessee deployed with the new warhead in December, according to the Federation of American Scientists (USN)

By The Maritime Executive 02-04-2020 08:19:00

The U.S. Navy is now deploying a low-yield nuclear weapon aboard some of its nuclear ballistic missile submarines. The new five-kiloton weapon could be used for smaller targets than the strategic 100-kiloton or 475-kiloton warheads currently in circulation among the service's 14 SSBNs. 

"The U.S. Navy has fielded the W76-2 low-yield submarine-launched ballistic missile (SLBM) warhead," said John Rood, under secretary of defense for policy, in a statement Tuesday. "This supplemental capability strengthens deterrence and provides the United States a prompt, more survivable low-yield strategic weapon." According to Rood, the advantage of a low-yield weapon is that it shows potential adversaries that the United States has a broad range of options under "any threat scenario" and that there is no advantage in a "limited nuclear employment." 

The W76-2 was first disclosed to the public in the Trump administration's 2018 Nuclear Posture Review (NPR). The NPR describes it as a response to an equivalent Russian capability, and according to the Federation of American Scientists, its development is motivated in part by the perception that Russia might consider a limited low-yield nuclear strike in the event of a conflict in Europe - without fear that the U.S. would respond in kind.

\With a small nuclear weapon on a proven sub-launched ballistic missile, American forces now have the ability to reliably penetrate Russian air defenses and deliver a proportionate response. Unlike cruise missiles and fighter-dropped bombs, the U.S. Navy's Trident II D5 SLBM is a genuine intercontinental delivery platform: it has a standoff distance of at least 4,000 nautical miles, multiple reentry vehicles and a terminal approach speed of about Mach 24, making it exceptionally difficult for an adversary to stop. 

Tactical-sized nuclear weapons have long drawn scrutiny for potentially "lowering the bar" for nuclear arms use: as the potential damage is small relative to a megaton-sized strategic warhead, a kiloton-sized bomb might prove more tempting to actually launch during a conflict. The NPR addressed this criticism, asserting that the new bomb is “not intended to enable, nor does it enable, ‘nuclear war-fighting.’" 

However, the Federation of American Scientists suggests that the delivery vehicle effectively makes the W76-2 unusable except in an attack against a small regional opponent. The low-yield bomb would launch aboard the same ballistic missile used for America's highest-yield strategic weapons, and if deployed in retaliation against Russian forces, it would create a signaling problem. Russia would have a narrow window in which to decide whether an inbound Trident II carried a few very small bombs or up to eight city-size bombs - and whether to begin a full-scale nuclear response.