At a vast tract of uninhabited desert in southern Nevada, hundreds of moonlike craters dimple the wasteland, remnants of Cold War nuclear explosions that melted the bedrock and fused the sand to ensure that America could take part in the unthinkable: global thermonuclear war. The crowds of scientists and generals are long gone–the U.S. hasn’t tested a nuke since 1992, when then President George H.W. Bush declared a self-imposed testing moratorium. But the Nevada National Security test site is not completely abandoned. A skeleton crew of custodians oversees the long dormant facility, less than 90 miles northwest of Las Vegas, standing by to turn the lights back on if the day ever comes.

It may come sooner than many thought.

Since 1993, the Department of Energy has had to be ready to conduct a nuclear test within two to three years if ordered by the President. Late last year, the Trump Administration ordered the department to be ready, for the first time, to conduct a short-notice nuclear test in as little as six months.

That is not enough time to install the warhead in shafts as deep as 4,000 ft. and affix all the proper technical instrumentation and diagnostics equipment. But the purpose of such a detonation, which the Administration labels “a simple test, with waivers and simplified processes,” would not be to ensure that the nation’s most powerful weapons were in operational order, or to check whether a new type of warhead worked, a TIME review of nuclear-policy documents has found. Rather, a National Nuclear Security Administration official tells TIME, such a test would be “conducted for political purposes.”

The point, this and other sources say, would be to show Russia’s Vladimir Putin, North Korea’s Kim Jong Un, Iran’s Ayatullah Ali Khamenei and other adversaries what they are up against.

President Trump has not ordered such a test, but even the consideration of a show of force–by the nation that announced the atomic age by dropping nuclear weapons on Japanese cities in August 1945–marks a provocative shift from the sober, almost mournful restraint that has characterized the U.S. posture toward the weapons for decades. To prevent nuclear war and the spread of weapons to non-nuclear states, the strategy of Republican and Democratic Commanders in Chief alike has been to reduce nuclear arsenals and forge new arms-control agreements.

The Trump Administration, by contrast, is convinced that the best way to limit the spreading nuclear danger is to expand and advertise its ability to annihilate its enemies. In addition to putting the Nevada testing ground on notice, he has signed off on a $1.2 trillion plan to overhaul the entire nuclear-weapons complex. Trump has authorized a new nuclear warhead, the first in 34 years. He is funding research and development on a mobile medium-range missile. The new weapon, if tested or deployed, would be prohibited by a 30-year-old Cold War nuclear-forces agreement with Russia (which has already violated the agreement). And for the first time, the U.S. is expanding the scenarios under which the President would consider going nuclear to “significant non-nuclear strategic attacks,” including major cyberattacks.

A 1952 nuclear detonation at the Nevada Proving Grounds, which Trump has ordered to prepare for resuming tests. Photograph by Bettmann Archive/Getty Images

“We must modernize and rebuild our nuclear arsenal, hopefully never having to use it, but making it so strong and powerful that it will deter any acts of aggression,” Trump said on Jan. 30 during his State of the Union address. “Perhaps someday in the future there will be a magical moment when the countries of the world will get together to eliminate their nuclear weapons. Unfortunately, we are not there yet.”

The rapid strategic changes have been matched by Trump’s norm-breaking rhetoric. Previously, every U.S. Administration since Dwight D. Eisenhower’s had avoided referring to the prospect of launching nuclear war and explicitly maintained, advanced or defended treaties designed to limit the spread of nuclear arms. Trump has openly threatened to unleash “fire and fury like the world has never seen,” and has been hostile toward international agreements. He reportedly called for more, not fewer, nuclear weapons in a July 20 Pentagon briefing, where military advisers were upbraided for presenting global reductions in nuclear stockpiles as progress.

Trump has criticized New START, which reduces and limits nuclear arms in the U.S. and Russia, as a bad deal. He has repeatedly questioned the multilateral deal under which Iran suspended its nuclear program, and promised to decertify it in May if changes aren’t made. He has publicly undermined Secretary of State Rex Tillerson’s diplomatic talks aimed at denuclearizing the Korean Peninsula, instead warning North Korea about his “much bigger & more powerful” nuclear button. “The long-standing strategic policy of the United States has been to reduce the role and number of nuclear weapons,” says Andrew Weber, who spent 30 years on nuclear-weapons issues in the State and Defense departments before retiring in 2015. “That idea seems to have been balled up and thrown out the window.”

The Trump team says it is responding to bad policy by past Administrations that left the U.S. vulnerable as other countries broke their word, and non-nuclear countries decided to pursue the weapons. “The President hates bad deals,” one senior Administration official tells TIME. “There’s a view of arms control as an intrinsic good, per se. Any agreement is a good agreement. That’s not where we are.” Aggressively responding to violations of treaties, launching new nuclear-weapons programs and reminding the world about the power of the U.S. nuclear arsenal, officials say, is the best way to deter others from expanding, or seeking, arsenals.

Foreign nations have issued dire warnings in response. China’s Ministry of National Defense in January urged the Trump government to abandon a “Cold War” mind-set, and view matters more “rationally and objectively.” Russian President Vladimir Putin in December accused the U.S. of violating a landmark Cold War–era nuclear arms deal and carrying out an aggressive military policy that “seriously affects security in Europe and in the whole world.” Both China and Russia are upgrading their nuclear weapons. Other nuclear powers, such as North Korea, Pakistan, India and Israel, continue to build new systems.

Rather than dissuading such efforts, arms-control experts from both political parties say, Trump’s moves will accelerate them. A new nuclear-arms race would not be limited to two superpowers seeking strategic balance in a Cold War but would include many nations, including foes in regions where hot wars are a regular occurrence.

“The new arms race has already begun,” says former Defense Secretary William Perry. “It’s different in nature than the one during the Cold War, which focused on quantity and two superpowers producing absurd numbers of weapons. Today it is focused on quality and involves several nations instead of just two. The risk for nuclear conflict today is higher than it was during the Cold War.”

The Trump administration is planning to take a step toward developing a new generation of nuclear weapons this month in its Nuclear Posture Review, a strategy document for the U.S. nuclear arsenal. Since the end of the Cold War, the U.S. has not designed any new nuclear weapons as it and Russia have worked to scale back their strategic arsenals. A draft proposal of the 64-page document, published in January by the Huffington Post, included two new sea-launched weapons, one outfitted with a small atomic warhead for battlefield use.

The new warhead, known as a tactical nuclear weapon, would be delivered by a submarine-launched missile against an advancing army. It differs from a strategic weapon, which is designed to destroy cities and hardened military targets. America needs battlefield nukes, the Trump team says, to match and deter adversaries’ tactical arsenals. In an escalating fight with Russia or China, the U.S. military could engage in a “limited nuclear war” rather than leveling whole cities with strategic weapons. Air Force General Paul Selva, vice chairman of the Joint Chiefs of Staff, tells TIME the President needs options. Trump and his successors should not face a choice between killing millions of civilians or backing down, he says. “It makes people uncomfortable to hear about nuclear war–fighting and presenting options to the President, whomever that person might be,” Selva says. “Strategic stability in the world between our nuclear competitors and our nuclear peers has been assumed. It is not a birthright.”

Trump’s new plan also expands the President’s “first use” of nuclear weapons to circumstances that include “non-nuclear strategic attacks” against the U.S. or its allies. That could mean cyberattacks on nuclear command and control systems or civilian infrastructure, like the electricity grid or air-traffic-control system, arms-control experts have concluded. Previous Administrations limited the threat of a nuclear response to mass-casualty events, like chemical- and biological-weapon attacks. Stephen Schwartz, a nuclear weapons policy expert, said the key concern is the expansion of the nuclear umbrella to “include these new and not extreme possibilities, thus dramatically lowering the threshold for nuclear use.”

The Trump plan also takes a new, skeptical approach to nuclear arms-control agreements. In the 2018 Pentagon budget, Trump included funding for the development of a new missile. If tested or deployed, the missile would violate a 30-year-old arms-control pact with Russia, the Intermediate-Range Nuclear Forces (INF) Treaty. Unlike his predecessors, Trump is directly confronting Russia’s prior violation of the treaty, says David Trachtenberg, Defense Undersecretary for Policy, who helped oversee the new plan. “The world is not as benign as some hoped it would be,” he says.

Trump’s nuclear moves, rolled out in policy papers and secret briefings over the past year, have garnered responses abroad ranging from quiet concern to outrage.

On Nov. 8, nearly five weeks before Trump approved research on the new missile, Secretary of Defense James Mattis assembled the defense ministers of the member-countries of the North Atlantic Treaty Organization, the 29-nation alliance that contained and defeated the Soviet Union in the Cold War. Convened inside a secure conference room under NATO’s highest security classification, known ominously as “Cosmic Top Secret,” the Mattis briefing laid out the American intelligence case indicating Russia’s violation of the INF treaty.

U.S. intelligence agencies had captured overhead imagery and additional information that Moscow had for years been testing a treaty-violating cruise missile at the Kapustin Yar rocket-launch test site in western Russia, Pentagon sources tell TIME. Now the missile had been deployed with two different Russian military units, putting European capitals at risk. The weapon was derisively nicknamed the SSC-8 “Screwdriver” by NATO analysts because “Russia used it to screw us,” say former U.S. officials.

A Cold War test in March 1953 in Nevada showed the impact of a 16-kiloton, tower-detonated nuclear warhead Corbis/Getty Images

The Russian cruise missile that violated the treaty could be launched without giving allies much advance time to determine what was coming their way. Leaders would have to quickly discern the blip on their radar screens and decide whether to respond in kind. The INF agreement, signed by President Ronald Reagan and Soviet Union leader Mikhail Gorbachev in December 1987, was the only nuclear arms-control agreement to eliminate a class of nuclear weapons. It forced the superpowers to scrap more than 2,600 missiles with ranges of about 310 to 3,420 miles–weapons considered destabilizing to Europe because they could deliver a nuclear strike in less than 10 minutes.

But if Europeans were concerned about Russia’s violation of the accord, they feared that the Trump Administration’s response would distract from it, said Kingston Reif, director for disarmament and threat reduction policy at the Arms Control Association. The last thing Europeans want is Moscow and Washington launching a new arms race in Europe. “There is no indication that NATO supports a new [missile], and attempting to force it upon the alliance would be incredibly divisive,” Reif says. “It is thus a weapon to nowhere.” Three days after Trump signed the defense bill, NATO issued a statement touting the INF treaty as “crucial to Euro-Atlantic security” and reiterated that “full compliance” was essential. NATO also called on Russia “to address these concerns in a substantial and transparent way.”

Arguments over U.S.-Russia nuclear deployments are not new. Strategists have long disagreed about whether to counter Moscow’s nuclear threat with escalation or restraint. It’s a high-stakes game of nuclear poker. The Trump Administration, in its aggressive approach, is betting on coercion. “We have to have this strong stance in order to get Russia to return to the negotiating table,” says Laura Cooper, a top Pentagon Russia expert. “But we are not throwing out the treaties that have served us so well in the past decades.”

If they can’t fix INF, officials tell TIME, the Trump Administration is not willing to engage on future arms agreements with Russia. That’s a particular problem, because New START, a linchpin arms-control agreement, will expire in three years. The 2010 deal limits each side to 1,550 deployed nuclear warheads. If it sunsets, it will be the first time the effort to limit the strategic stockpiles in the U.S. and Russia has lapsed since 1991.

Former U.S. Senators Sam Nunn and Richard Lugar, whose bipartisan partnership was crucial to gaining ratification of nuclear-weapons treaties in the chaotic years following the Cold War, fear an end to arms control altogether. “We have severe erosion,” Nunn says. “We are going into a period of much greater risk in the nuclear arena.” Says Lugar: “The trend has been moving away from these sorts of international agreements, which is deeply troubling–and frankly dangerous.”

At the same time, the U.S. and Russia are accelerating their spending on nuclear forces. The current U.S. plan would require spending $1.2 trillion to modernize the aging U.S. “nuclear triad” of bombers, submarines and land-based missiles over the next three decades. The U.S. is reinvesting in the labs and factories that produce warheads. While the U.S. nuclear stockpile has been slashed over the past 30 years, the U.S. military has said the remaining arsenal is unmatched.

Russia is in the midst of overhauling its nuclear forces, including new ICBMs, ballistic-missile submarines and modernized heavy bombers. It’s developing a massive RS-28 Sarmat ICBM that boasts countermeasures designed to elude U.S. antimissile systems. It’s also practicing nuclear snap drills that involve missile launches from the air, land and sea.

The rest of the world is not blind to the accelerating U.S.-Russia competition. While the two nations account for nearly 93% of the world’s nuclear arsenal, there are now nine countries with stockpiles. Not only do they have no plans for disarmament, but they aren’t seeking reductions. The number of nuclear weapons in the world has declined since the Cold War, from a peak of about 70,300 in 1986 to 14,550, according to the Federation of American Scientists (FAS). But the pace of reductions has drastically slowed.

Around the globe, the perceived value of acquiring nuclear weapons has gone up, while the repercussions of violating treaties has declined, says Hans Kristensen, director of the nuclear-information project at FAS. “We’re certainly in a dynamic strategic competition where all sides are arming themselves,” he says. “If the dynamic is not stopped and reversed, it will almost inevitably escalate into an arms race. That is in the nature of the beast.”

If Trump undoes the nuclear deal with Iran, analysts fear that Tehran will sprint for a weapon. Its regional rival Saudi Arabia could then develop its own atomic weapon, or import one from close ally Pakistan, which has its own fast-growing nuclear arsenal to counter arch-rival India’s. (Pakistan is building up its stockpile of tactical nuclear weapons.) China now has a nuclear-powered submarine, known as the Jin-class, that gives its military the ability to launch ICBMs from the sea.

Few threats loom larger, or more immediate, for the U.S. than North Korea. Pyongyang has launched a record 23 missiles during 16 tests since Trump took office. It has tested at least six nuclear warheads, and U.S. intelligence believes it has made progress on miniaturizing a nuclear warhead to mount on a missile. The isolated nation’s most recent launch, on Nov. 29, climbed 2,800 miles into outer space, more than 10 times higher than the International Space Station. If that flight path were flattened out, it could have hit New York City, Washington or nearly any other city in America.

Hawaii’s false ballistic missile alert on Jan. 13 was the most visceral reminder yet of what’s at stake. Ballistic missile threat inbound to Hawaii. Seek immediate shelter. This is not a drill, read the emergency-system alert pushed to people’s smartphones statewide. It took 38 minutes to issue an all clear for the mistake; a worker had mistaken a drill for the real thing.

Disarmament experts warn that this is just one of the risks in a new era of brinkmanship. “Trump has not said what the last 10 Presidents have said, which is we will lead on arms-control agreements and nonproliferation issues,” says Thomas M. Countryman, a 35-year career diplomat who retired last year after leading the State Department’s nonproliferation efforts. “I think that is an indication that the importance of appearing masculine is more important than actually reducing the threat of nuclear warfare.”

Philip Coyle, a former test director at the Nevada Test Site, also warned about the chance of miscalculation. “This is a time where we need more thought about where we’ve been and where we’re headed,” he said. “There is little room for error.”

Americans of a certain age will remember the Doomsday Clock maintained by the Bulletin of the Atomic Scientists. It expresses the risk of nuclear annihilation as time remaining until midnight. On Jan. 26, citing Trump’s moves, it pushed the second hand 30 seconds forward, the closest Doomsday has loomed since 1953, when the U.S. and Russia first tested hydrogen bombs within months of each other.

This appears in the February 12, 2018 issue of TIME.

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Write to W.J. Hennigan at william.hennigan@time.com.