In June 2019, the director of the Pentagon’s main intelligence agency made an eyebrow-raising allegation about Russia and its nuclear programs: Moscow is testing its atomic weapons.
"The U.S. government, including the Intelligence Community, has assessed that Russia has conducted nuclear weapons tests that have created nuclear yield,” Lieutenant General Robert Ashley said.
China may also be conducting its own tests, Ashley added, possibly by using “zero-yield” methods in which no actual atomic explosion -- a fission chain reaction -- takes place.
Fast forward six years. The United States and Russia are on the verge of a new arms race. The Kremlin is boasting that it is developing new, nuclear-capable superweapons. And President Donald Trump is threatening to resume US nuclear tests.
“Russia's testing and China's testing, but they don't talk about it,” Trump said in an interview with CBS News recorded on October 31. “No, we're gonna test, because they test and others test.”
That claim is subject to debate. Regardless, the threat has drawn criticism from Moscow and cheers from US national security hawks, not to mention handwringing among arms control advocates.
After years of collapsed or eroded arms control agreements -- the Intermediate-Range Nuclear Forces Treaty, the Anti-Ballistic Missile Treaty, the Open Skies, New START -- advocates worry that the global pact banning nuclear tests may be next.
At a meeting of Russia’s Security Council on November 5, Defense Minister Andrei Belousov called for preparations to resume nuclear testing -- at ranges on the Arctic archipelago of Novaya Zemlya.
Confused by all the treaties? Don’t know what a “yield” is? We’ve got you covered: Read on.
Testing, Testing
The last time the United States used explosives in its weapons arsenal to split a uranium or plutonium isotope and spark the nuclear chain-reaction known as fission was in the dusty landscape of Nevada in 1992. It wasn’t a mushroom cloud like you see in the movies -- those went out of favor in the 1960s, with a treaty -- but an underground blast.
Moscow’s last fission test of a weapon? That was in 1990, a year before the Soviet collapse, on Novaya Zemlya. Beijing’s was in 1996 at Lop Nur, in the windswept reaches of the far western Xinjiang province.
That same year, the Comprehensive Nuclear-Test-Ban Treaty (CTBT) came into being. Since that time, only Pakistan and India have conducted similar critical tests -- and North Korea has conducted half a dozen, most recently in 2017.
Generally speaking, nuclear tests that involve actual explosions of fissile material are relatively easy to detect.
Highly sensitive seismic monitoring devices, like those that monitor earthquakes, can pick up shock waves from a blast underground, where all tests have occurred for decades. Aircraft equipped with sophisticated “sniffing” equipment can register radioactive isotopes floating into the atmosphere, telltale signs of a nuclear detonation.
Noncritical. Critical. Supercritical.
The end of the Cold War, and of the Soviet-US arms race, meant major cuts to nuclear arsenals and a downgrade of budgets and investments into the infrastructure needed to plan the bombs and build them.
All nuclear-armed countries need to ensure that their arsenals can devastate as they’re expected to, so testing continues -- just not in a mushroom-cloud sort of way. Noncritical tests, in which explosives and fissile material are used but not detonated to cause fission, are allowed under the CTBT. Researchers use supercomputers and powerful lasers to test or mimic fission reactions.
Trump first suggested the possibility of new tests in a social media post just before meeting with Chinese President Xi Jinping in South Korea. He expanded on that later in his CBS News interview.
US officials have maintained a test site in Nevada where subcritical experiments have continued. However, doing a full-blown fissile explosion could not happen right away.
“The US could not conduct a test in days or weeks but, depending on the details of the test and the diagnostics, we could resume testing in months to a few years,” said Jill Hruby, a former director of the Sandia National Laboratories in New Mexico and former head of the National Nuclear Security Administration (NNSA), which manages storage and tests of the US nuclear arsenal.
Energy Secretary Christopher Wright, whose department oversees the NNSA, later clarified Trump’s comments.
"I think the tests we’re talking about right now are system tests," Wright said in an interview with Fox News on November 2. "These are not nuclear explosions. These are what we call noncritical explosions."
US authorities have ample data from previous underground testing, plus laboratory testing and subcritical experiments, according to Hruby -- one argument, she said, for not resuming full tests.
“Additionally, if we start testing it is clear others would resume or start testing,” she said. “Once testing is resumed, it is highly likely in my opinion that new types of devices will be explored, fueling more arms racing.
“Finally, while testing can be safe, accidents can occur. I think most people would agree that large-scale nuclear testing is not something that environmentally benefits our planet and humanity,” she said.
Real World Testing
In April, the US State Department released its annual report on countries complying with arms control treaties. The report said Russia had conducted “supercritical” nuclear weapons tests in past years, but failed to notify the US or other countries as required under a 1974 treaty that also put a cap on the size of underground explosive blasts.
“Concerns remain due to these past activities and the uncertainty and lack of transparency relating to Russia’s activities at Novaya Zemlya,” the report said.
Broadly speaking, the term “supercritical” refers to a fission reaction, when an isotope is split and causes a full-blown chain reaction. “Noncritical” or ‘subcritical” do not.
For national security hawks -- in Washington or Moscow or even Beijing -- the world has changed. China, which is not constrained by the soon-expiring New START Treaty between Washington and Moscow, is expanding its arsenal. The Kremlin is modernizing its arsenal and rolling out new intercontinental ballistic missiles like the Sarmat and other nuclear-capable weapons like the Burevestnik and the Poseidon, an unmistakable signal.
Days after Trump’s comments, CIA Director John Ratcliffe said in a post on X that Trump “was right” about Chinese and Russian testing.
“The United States has to maintain technical and numerical superiority to the combined Chinese and Russian nuclear stockpiles,” Robert O’Brien, who served as White House national-security adviser during Trump’s first term, wrote in a Foreign Affairs article last year. “To do so, Washington must test new nuclear weapons for reliability and safety in the real world for the first time since 1992 -- not just by using computer models.”
“If China and Russia continue to refuse to engage in good-faith arms control talks, the United States should also resume production of uranium-235 and plutonium-239, the primary fissile isotopes of nuclear weapons,” he wrote.
O’Brien did not respond to a request for comment sent to his Washington firm.
In Moscow, Russian officials have criticized Trump’s pledge to resume testing and denied the accusation that they had conducted actual nuclear tests.
At a televised Security Council meeting at the Kremlin on November 5, President Vladimir Putin echoed Belousov’s remarks and ordered officials to make proposals for the “possible start of work to prepare for nuclear weapons testing.” But he also said Moscow had no intention of violating the CTBT.
If the Trump administration does move forward with full testing, it would likely spark its own race, as other nations -- China first and foremost -- move to resume testing. That would push the CTBT agreement toward outright collapse. Russia “de-ratified” the treaty in 2023; Washington has signed it but not ratified it. Some administration officials have called for “un-signing” it. China has signed but not ratified the pact.
“Explosive testing would open the way for other nations to do the same. They have not done as many tests as the US has and would benefit more from explosive testing,” said Cheryl Rofer, a retired nuclear scientist at the Los Alamos National Laboratory, where US researchers developed the first nuclear weapons in the 1940s.
A return to full-scale testing would also likely doom the New START treaty, which caps the size of the Russian and American nuclear arsenals, experts say. That treaty is due to expire next year, and no negotiations are under way to replace it.
In September, Putin proposed adhering to the treaty’s requirements for a year after it expires in early February, something the White House signaled openness to.
