The letter, sent in April but not previously reported, draws the UK into a US political debate, pitting the Trump administration against many Democrats and arms control groups over whether the $ 14 billion W93 program is needed . The US Navy already has a choice of two warheads for its submarine-launched Trident missiles.
The close cooperation on the W93 casts further doubt on the actual independence of British deterrence – Parliament first heard about it when US officials accidentally exposed Britain’s involvement in February – and the two countries’ commitment to disarmament.The UK is also backing the administration’s efforts to speed up work on the warhead and its surprise request for $ 53 million for initial weapons design work in the 2021 budget, two years ahead of the previous schedule.
Skeptics believe the rush is aimed at blocking funding ahead of the election. A Biden administration would be likely to review or even cancel the W93 program.
“These are difficult times, but it is essential that we demonstrate transatlantic unity and solidarity during these difficult times,” Wallace told members of the House and Senate Armed Services Committees. “Funding for the Congress in  The W93 program will ensure that we continue to deepen the unique nuclear relationship between our two countries, enabling the UK to provide safe and assured deterrence at sea for decades to come.
The British intervention comes as the initial funding for the warhead is on the line. It has been approved by the House and Senate armed services committees, but at least temporarily blocked by an energy and of the House’s water last month.
Congressional staff said they couldn’t recall such a direct UK intervention in a US nuclear weapons debate.
“We’ve never received a letter like this before, so it was a little surprising that this was the issue they chose to weigh in,” a committee aide said.
The UK insists its Trident nuclear deterrent system is stand-alone, but the two countries share the same missiles and coordinate work on the warheads. The current British Trident warhead, the Holbrook, is very similar to the W76 warhead, one of two the U.S. Navy uses in its own Trident II missiles.
The US and UK versions of the W93 are also expected to closely resemble each other. Both countries will use the same new MK7 aeroshell, the cone around the warhead that allows it to enter Earth’s atmosphere, which will cost several hundred million dollars more.
Not much has been disclosed about the W93, but it is believed to be based on a design that was tested during the Cold War but was not in U.S. stock at the time. This will potentially be the first new warhead design in the U.S. stockpile since the Cold War and is expected to be significantly more efficient than the current W76, which is already six times more powerful than the bomb dropped on Hiroshima ago. 75 years old next week.
The funding request for the W93 is particularly controversial in the United States as the W76 and a higher efficiency submarine-launched ballistic missile (SLBM) warhead, the W88, have already received upgrades from several billion dollars.
“This is excess on top of excess,” said Kingston Reif, director of disarmament and threat reduction policy at the Association for Arms Control. “We already have two SBLM warheads. The W76 just went through a major life extension program and is expected to be good through the early 2040s, and the W88 is undergoing a major modification.
“The US can continue to aid the UK’s arsenal without rushing the development of an unnecessary third SLBM warhead, a redesign of at least $ 14 billion,” Reif added.
The total cost of the US nuclear weapons modernization program is expected to well exceed $ 1 billion.
The United States and Russia, which are also modernizing their arsenals and developing new weapons, together account for more than 90% of all nuclear warheads on the planet, and the two countries are increasingly emphasizing this in their rhetoric. and their defensive postures.
Under Donald Trump, the United States has now left three nuclear deals and his administration is reluctant to extend the last major arms control deal with Russia, the 2010 New Start Treaty, which is due to expire in February.
The bonfire of nuclear deals, combined with the huge sums spent on weapons like the W93, pose a threat to the 1968 Nuclear Non-Proliferation Treaty, the fundamental bargain through which nuclear-free countries have pledged not to acquire them on the condition of recognized nuclear powers. (the US, UK, France, Russia and China) have taken steps to disarm, in accordance with Article Six of the Treaty.
“When I look at something like the W93, it is not, in and of itself, a violation of article six,” said Daniel Joyner, a University of Alabama law professor specializing in nuclear treaties. “This is just another data point to evidence, the current US and UK non-compliance with Article Six.”
In his letter to congressional committees, Wallace wrote: “Your support for the W93 program in this budget cycle is critical to the success of our replacement warhead program and the long-term viability of the UK’s nuclear deterrent and , therefore, in the future of NATO as a nuclear alliance. ”
Alexandra Bell, former State Department official and now senior policy director at the Center for Arms Control and Non-Proliferation, said the special relationship between the United States and the United Kingdom has shown greater solidarity in the promotion of new weapons than in arms control.
“The UK is noticeably absent when it comes to outright support for the New Start extension, but at the same time, it feels comfortable telling Members of Congress directly what they should be doing regarding our own. modernization plans, ”Bell said. “I think it’s weird.”
Asked about the purpose of Wallace’s letter, a spokesperson for the UK Ministry of Defense said: “The UK’s existing warhead is being replaced in order to respond to future threats and ensure our security. We have a strong defense relationship with the United States and will work closely with our ally to ensure our warhead remains compatible with the US Trident missile.
According to official figures, the US W76 warhead is viable until at least 2045 – and the UK version is expected to last until the end of the 2030s, so there is no urgent technical need for replacement.
Greg Mello, executive director of the Los Alamos Study Group, said nuclear hawks from the Pentagon, the National Nuclear Security Administration and the Los Alamos National Laboratory were pushing to freeze spending if there is a change in administration.
“They would love to see this program approved by Congress this year, and they are very close to it,” Mello said. “Once this program is registered, it will take more for a future administration to remove it.”