The U.S. Navy has reportedly sent an Ohio class ballistic missile submarine on patrol for the first time carrying Trident II submarine-launched ballistic missiles armed with the new and controversial low-yield W76-2 nuclear warhead. This news comes nearly a year after the United States announced it had produced the first of these warheads. Proponents say the warheads are necessary to give the U.S. government added flexibility to respond to certain crises, including limited nuclear strikes, but critics contend that they raise the likelihood of the United States employing nuclear weapons, to begin with. The Federation of American Scientists first reported the deployment on Jan. 20, 2020. The Ohio class ballistic missile submarine USS Tennessee left its homeport at Naval Submarine Base Kings Bay in Georgia in late December 2019 for a deterrent patrol armed with an unknown number of Trident IIs carrying W76-2s.

"We estimate that one or two of the 20 [Trident II] missiles on the USS Tennessee and subsequent subs will be armed with the W76-2, either singly or carrying multiple warheads. Each W76-2 is estimated to have an explosive yield of about five kilotons," according to the Federation of American Scientists. "The remaining 18 missiles on each submarine like the Tennessee carry either the 90-kiloton W76-1 or the 455-kiloton W88. Each missile can carry up to eight warheads under current loading configurations." So, the W76-2, with its estimated yield of five kilotons, has a yield 18 times smaller than the existing W76-1 and is more than 90 times smaller than the W88. NUKEMAP, a map tool that nuclear weapons historian Alex Wellerstein, presently a professor at Stevens Institute of Technology in New Jersey, first put online in 2012, estimates that a W76-2 that detonates on the ground would create a fireball just over 490 feet wide, wherein anything would be incinerated, and cause varying levels of damage to anything within a circle around ground zero just under one and a half miles in diameter. By comparison, the W88's fireball would be just under 2,330 feet wide and there would be degrees of damage across an area around 18 miles in diameter. The spread of deadly radiation and fallout would also be factors within these areas, as well as beyond, depending on prevailing weather patterns.

NUKEMAP A comparison of how Washington, D.C. might be impacted by the detonation of, from left to right, a W88, a W76-1, and a W76-2, as a generic example, according to NUKEMAP's models. The gray outer circle is the maximum extent of light damage, such as broken windows. The yellow circle, clearly visible in the cases of the W88 and W76-1, is the extent of thermal raditation, which can cause third degree burns. The other colored bands cover more extensive damage and the spread of radiation, as well as the immediate fireball, outlined in red.

President Donald Trump's Administration codified plans to develop a low-yield warhead for the Trident II missile in the 2018 Nuclear Posture Review. The National Nuclear Security Administration (NNSA), the division of the Department of Energy directly responsible for overseeing America's nuclear stockpile, announced it had built the first W76-2 at the Pantex Plant in Amarillo, Texas in February 2019. At that time it said that it planned to deliver the first of these warheads to the Navy by the end of the fiscal year, which wrapped up on Sept. 30, 2019.

NNSA The official logo for the W76-2 warhead program. Mk 4A refers to the re-entry vehicle that carries the warhead.

The exact configuration of the W76-2 is classified, but it is known to be a derivative of the W76-1, which was itself a product of a life-extension program for the original W76 warheads that NNSA also completed last year. The W76 and W76-1 are understood to be two-stage thermonuclear weapons and previous reports have posited that the new W76-2 may simply eliminate the second stage to produce a significantly lower yield. This would also help explain the speed at which NNSA could develop and field the warhead.

NNSA An official infographic on the W76-1, which also uses the Mk 4A re-entry vehicle.

"We estimate approximately 50 W76-2 warheads were produced, a low-cost add-on to improved W76 Mod 1 strategic Trident warheads which had just finished their own production run," the Federation of American Scientists said in their report. At present, the Navy plans to eventually deploy Trident II missiles armed with the new warheads on its future Columbia class ballistic missile submarines, which are scheduled to begin sailing deterrent patrols in 2031.

USN An artist's conception of the first-in-class USS Columbia.

USN The Ohio class ballistic missile submarine USS Rhode Island fires a Trident II missile, with no warheads of any kind fitted, during a test in 2019.

A recent push by some members of Congress to cancel or curtail the W76-2 program as part of negotiations over the annual defense policy bill, or National Defense Authorization Act, for the 2021 Fiscal Year, ultimately collapsed. Opposition to the low-yield warhead remains and there may be additional legislative efforts aimed at removing it from America's nuclear arsenal in the future. In the meantime, however, the Navy's Ohio class ballistic missile submarines look set to sail their routine deterrent patrols carrying Trident II missiles carrying the new, lower-yield warheads. Contact the author: joe@thedrive.com