By Lisbeth Gronlund

When President Trump took office, he inherited an arsenal of some 2,000 ready-to-use nuclear weapons. It consists of five different warheads on long-range missiles in underground silos, on submarines, and on air-launched cruise missiles, and several types of bombs that can be dropped from airplanes. These weapons have an astonishingly wide range of explosive yields—from 0.3 kiloton (50 times smaller than that of the bomb that destroyed Hiroshima) to 1.2 megatons (80 times greater).

But this array of destructive capacity is apparently not enough for the Trump administration, which plans to deploy a new warhead on submarines: the W76-2 Trident warhead, with a reported yield of 6.5 kilotons, would replace some of the existing, higher-yield (100-kiloton) W76 warheads. It will be relatively quick and inexpensive to produce the new “low-yield” W76-2 warheads, which could be placed on submarines before Trump’s term is up. Of course, “low-yield” is a misnomer—if used against a Russian city, this weapon could kill tens of thousands of people and injure far more.

In its 2018 assessment of US nuclear forces—called the Nuclear Posture Review (NPR)—the administration argues that the new Trident warhead “will help counter any mistaken perception of an exploitable ‘gap’ in US regional deterrence capabilities.” The term “regional deterrence capabilities” is code for low-yield nuclear weapons that would be used in a regional, conventional conflict.

In other words, according to the NPR, the United States needs the new W76-2 warhead because, without it, Russia will mistakenly believe it could use nuclear weapons in a conventional conflict without fearing a US nuclear response because of a perceived gap in US low-yield capabilities.

Claiming there is a gap is absurd. The arsenal already includes warheads with yields of 5 and 10 kilotons.

A renewed interest in nuclear war-fighting is evident throughout the NPR, which calls for tighter integration of US nuclear and conventional forces, including training and exercising with integrated units, so US forces can fight “in the face of adversary nuclear threats and employment.” That means preparing to fight even if Russia uses low-yield nuclear weapons, and the United States responds in kind.

Deploying this new warhead, which adds to current US low-yield nuclear capabilities, would take US policy in precisely the wrong direction, increasing the role of nuclear weapons in US security plans and indicating that the United States considers such weapons to be usable.

Lisbeth Gronlund, a senior scientist at UCS, codirects the organization’s Global Security Program. You can read more of her work on the All Things Nuclear blog.