The US Navy has deployed the new low-yield Trident W76-2 warhead on a nuclear submarine.

The warhead is believed to be deployed on the Ohio-class ballistic missile submarine USS Tennesse (SSBN-734). The submarine is currently on patrol in the Atlantic Ocean, according to the Federation of American Scientists (FAS).

The first production unit (FPU) of the W76-2 was completed at Pantex in February 2019. Approximately 50 W76-2 warheads would have been produced.

However, the National Nuclear Security Administration (NNSA) has not disclosed the total number of planned W76-2 warheads.

The desire to produce the W76-2 was announced in the February 2018 Nuclear Posture Review (NPR). It is being developed for existing submarine-launched Trident II (D-5) missiles.

Around $65m has been devoted by Congress for work on the W76-2 warhead in FY2019, with $10m allocated to complete the work in FY2020.

It is a low-cost add-on to improve the W76 Mod 1 strategic Trident warhead.

The armoured weapon system is configured for primary-only detonation and is lighter than the current W76-1 warhead.

FAS nuclear information project director Hans Kristensen was quoted by The Guardian as saying: “We have had conversations with people inside, and they’ve been pretty clear that this has happened.

“They see a need to talk about it to some extent because if people don’t know it’s out there, then how can it deter?

“This is a very rapid mind quick turnaround for a nuclear weapon, and that’s obviously because it was a fairly simple adjustment of an existing warhead.

“They have argued that this is to deter Russia, but it also has clear implications or potential use against other adversaries, not least North Korea and Iran.”