Trump’s vow to resume nuclear tests leaves experts puzzled

“I don’t have insights into the president’s intent," said Vice Adm. Richard Correll, at his Senate confirmation hearing to lead U.S. Strategic Command, after he was asked whether Trump wanted to step up missile flight tests or resume underground nuclear detonations for the first time in more than three decades.

Trump announced Thursday on social media that he had “instructed the Department of War to start testing our Nuclear Weapons," minutes before he met with Chinese leader Xi Jinping in South Korea. He offered no specifics when he spoke to reporters later on Air Force One as he flew back to Washington. The White House responded to questions by referring to his post.

Former U.S. officials and analysts have focused on three possibilities. One theory is that Trump might be jockeying for leverage in possible talks with Moscow and Beijing.

Trump posted his statement shortly after Russian President Vladimir Putin boasted about the successful tests of a nuclear-powered cruise missile that NATO has dubbed the Skyfall, and a nuclear-armed torpedo that could be used to attack ports.

Both of those Russian weapons have been under development for years. But Putin has touted them as the New Start treaty that restricts American and Russian long-range nuclear weapons is set to expire in February.

Russia has offered to keep the treaty’s weapons ceilings in place for another year and Trump has signaled he is open to the idea. But negotiations to hammer out the scope of such an understanding have yet to be arranged.

Another theory that has been put forward by U.S. lawmakers and former officials is that Trump is seeking more leeway for U.S. nuclear-test activities.

“Because of other countries testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis," Trump said. “That process will begin immediately."

The U.S. last conducted a nuclear-weapons test in 1992 and has joined Russia and China in observing moratoriums on underground nuclear blasts. China’s last test was in 1996, while Russia’s last known nuclear test was in 1990.

The U.S. intelligence community, however, has assessed that Russia has likely been carrying out small nuclear experiments with very low explosive power, which experts have dubbed “supercritical tests." And there have been concerns within the U.S. intelligence community that China might be undertaking similar activities as well.

“Russia and China have conducted supercritical weapons tests to advance their nuclear programs," said Sen. Tom Cotton (R., Ark.). He said Thursday that he believed Trump’s comments indicated he intends to follow suit.

Some former officials say that in the U.S., such supercritical experiments aren’t vital for determining the reliability of the stockpile: The Energy Department, which oversees development and testing of nuclear warheads, can validate the reliability of the stockpile by relying on advanced computer simulations and small experiments that don’t produce a nuclear yield, analysts said.

Still another possibility is that Trump wasn’t referring to testing nuclear devices at all, and that he meant instead that he wanted to step up flight tests of missiles that carry nuclear warheads.

“It could be that what he is talking about is delivery systems," Sen. Angus King, the Maine independent said at Correll’s Senate nomination hearing.

“I agree that could be an interpretation," Correll responded.

Trump said in his social-media post that the U.S. has the largest number of nuclear weapons and the most capable deterrent because of a modernization program he claims to have completed during his first term.

But the upgrading of the U.S. land- and submarine-based missiles and long-range bombers, which will cost well over a $1 trillion, was set in motion during the Obama administration and won’t be completed for well over a decade. And Russia has more than 4,300 weapons in its nuclear stockpile compared with some 3,700 on the part of the U.S., according to the Federation of American Scientists.

“Russia has the world’s largest inventory of nuclear warheads," said Hans Kristensen, the director of the nuclear information project at FAS.

A return to nuclear testing, if ordered by White House and funded by the Congress, wouldn’t be immediate. Former officials said it could take two years to prepare a major nuclear test in order to design the underground detonation, including the placements of instruments to measure its effects.

Preparations to carry out supercritical experiments such as those the Russians are suspected to have conducted could still take months or perhaps even as long as a year, a former official said.

The fundamental issue is whether the U.S. has more to lose than gain by ending the nuclear-test moratorium. China has conducted far fewer nuclear blasts than the U.S., experts note, and thus could learn more about how to develop new nuclear weapons if it resumed testing, too. While the U.S. has carried out more than 1,000 nuclear tests, China has conducted 45 tests.

Sen. Jack Reed of Rhode Island, who serves as the top Democrat on the Senate Armed Services Committee, said breaking the testing moratorium would prompt Moscow and Beijing to restart full-fledged testing.

U.S. nuclear testing, he added, would also provide justification for Pakistan, India and North Korea, which last tested in 2017, “to expand their own testing regimes, destabilizing an already fragile global nonproliferation architecture."