ARLINGTON, Va. — The U.S. National Nuclear Security Administration (NNSA) could turn the existing W76 warhead into the low-yield submarine-launched weapon requested by the Donald Trump administration by dialing back its explosive yield, a senior agency official said here Wednesday.
“A low-yield submarine-launched ballistic missile warhead capability, deemed the W76 Mod 2, will be fielded by configuring a small number of existing ballistic missile warheads for primary-only detonation,” Steven Erhart, who on Wednesday was the acting NNSA administrator, said at the ExchangeMonitor’s annual Nuclear Deterrence Summit.
Erhart was replaced on Thursday by Lisa Gordon-Hagerty, the Trump administration’s choice to replace Frank Klotz as head of the Department of Energy nuclear weapons agency. Erhart returned to his previous job as director of the NNSA’s policy office.
The current W76, like other thermonuclear warheads, has two explosive stages.
Erhart would not say whether the NNSA plans any work in the upcoming 2019 fiscal year to support W76 Mod 2 in particular, or a low-yield submarine-launched ballistic missile in general. The detailed NNSA budget justification released Friday acknowledges the Nuclear Posture Review’s directive to work on a low-yield warhead, but does not identify any requested funding for that program, or identify any associated deliverable.
The day after Erhart spoke, former NNSA Administrator Linton Brooks estimated it would cost tens of millions of dollars to create the W76 Mod 2, or something like it.
“And everything about it as a policy is probably the easiest thing we’ve done,” Brooks said during a panel discussion at the Deterrence Summit. “[W]hen we test fly W76s, we have a dummy secondary and a dummy primary. When we go to war with W76s, we have a real secondary and a real primary, and so to replace the real secondary with a dummy secondary is not … a technical challenge.”
The United States first fielded the W76 warhead in 1978. It is presently deployed aboard Trident II D5 missiles carried by Ohio-class ballistic missile submarines. The Sandia National Laboratories in Albuquerque, N.M., and the nearby Los Alamos National Laboratory designed the W76, which was built by Los Alamos.
The Nuclear Posture Review released by the Pentagon in early February calls for a new low-yield submarine-launched ballistic warhead, which the Trump administration says is needed to deter Russia from using a similarly powerful nuclear weapon to escalate a military conflict fought with conventional weapons.
Moscow might feel safe using using a smaller nuke, the White House believes, because it would be more powerful than conventional forces and might not provoke a nuclear counterpunch from a country without a low-yield option.
Besides the submarine-launched ballistic missile option, the Nuclear Posture Review also called for the NNSA and the Pentagon to study a new sea-launched, nuclear-capable cruise missile with a low-yield warhead.
