he US has begun making a new, low-yield nuclear warhead for its Trident missiles that arms control advocates warn could lower the threshold for a nuclear conflict.
The National Nuclear Security Administration (NNSA) announced in an email it had started manufacturing the weapon at its Pantex nuclear weapons plant in Texas, as ordered by Donald Trump’s nuclear posture review (NPR) last year.
The NNSA said the first of the new warheads had come off the production line and that it was on schedule to deliver the first batch – an unspecified number referred to as “initial operational capability” – before the end of September.
The new weapon, the W76-2, is a modification of the existing Trident warhead. Stephen Young, a senior Washington representative of the Union of Concerned Scientists, said its yield had most likely been cut by taking away one stage from the original two-stage, W76 thermonuclear device.
“As best we can tell, the only requirement is to replace the existing secondary, or second stage, with a dummy version, which is what they do every time they test fly a missile,” Young said, adding that the amount of tritium, a hydrogen isotope, may also be adjusted. The result would be to reduce its explosive power from 100 kilotons of TNT, to about five – approximately a third of the force of the bomb dropped on Hiroshima.
The Trump administration has argued the development of a low-yield weapon would make nuclear war less likely, by giving the US a more flexible deterrent. It would counter any enemy (particularly Russian) perception that the US would balk at using its own fearsome arsenal in response to a limited nuclear attack because its missiles were all in the hundreds of kilotons range and “too big to use”, because they would cause untold civilian casualties.
Low-yield weapons “help ensure that potential adversaries perceive no possible advantage in limited nuclear escalation, making nuclear employment less likely”, the 2018 nuclear posture review said.
Many critics say that is an optimistic scenario that assumes there will be no miscalculation on the US side.
“There are many other scenarios, especially with a president who takes pride in his unpredictability and has literally asked: ‘Why can’t we use our nuclear weapons?’”, Young said.
Melissa Hanham of the One Earth Future foundation pointed out that adversaries would have no way of knowing if a full-force Trident was being fired at them, or its low-yield cousin.