Afew days before Joe Biden left the White House, his under secretary for nuclear security at the Energy Department, Dr. Jill Hruby, took the stage at a Washington, DC, think tank and described in grim detail the instability of our nuclear-armed world.

Russia, Hruby said, has in recent years stationed tactical nuclear weapons in Belarus; withdrawn its ratification of the Comprehensive Test Ban Treaty; and lowered its threshold for nuclear weapons use. It also seems to be exploring new nuclear-weapons delivery technologies, including space-based weapons. Further south, China is rapidly expanding the size of its nuclear arsenal and appears to be moving away from a no-first-use policy for launching nuclear weapons. North Korea persists in building up its nuclear program, rattling the region with its regular missile tests, while Pakistan is developing its own intercontinental ballistic missile capabilities, and Iran continues to enrich uranium.

In her speech, Hruby did not offer many details about what US allies, such as Israel and India, are up to, although she might have: They too are contributing to the disequilibrium. Israel is perhaps the least transparent of the world’s nuclear powers, unwilling even to acknowledge that it has a weapons program. India, meanwhile, is actively building up its nuclear stockpile. France has signaled in recent months that it may try to establish its own “nuclear umbrella” in Europe as the United States wavers in its commitment to NATO. And in South Korea, officials have made noise in recent years about the possibility of obtaining nuclear weapons to counter their enemies in the North.

As for the United States, it is not merely “observing change,” Hruby assured her audience, “we are advancing change on our own.” The country, she said, is currently engaged in a massive nuclear “modernization” program, which will see it replace or upgrade every element of its nuclear stockpile over the next three decades while also developing new weapons, like a sea-launched nuclear cruise missile. Among other things, this modernization program will also reestablish key production capabilities that were lost at the end of the Cold War. The program, which President Barack Obama initiated in 2010, will cost more than $1.2 trillion—some say as much as $1.7 trillion—through 2046.

“With our eyes wide open,” Hruby told the crowd, “we have laid out a path to sustain credible nuclear deterrence.”

Hruby delivered this summation in the bloodless tone of the bureaucrat, but there was no mistaking her message: The status quo of the previous 80 years—in which there were only two dominant nuclear powers, each deterred from launch by the doctrine of mutually assured destruction—is over. We are entering a multipolar nuclear world, one where China joins Russia and the US as a peer and where the old nuclear guardrails are breaking down. Indeed, only one major arms-control treaty remains between the US and Russia—the New START treaty—which expires in February 2026. If the two countries fail to negotiate new nuclear restraints, they could begin “increasing the number of deployed nuclear warheads for the first time in 35 years,” said Daryl Kimball, the executive director of the Arms Control Association.

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Or, as Hruby observed: “It is a less predictable and more dangerous time.”

As she neared the end of her speech, Hruby made a point of saying that we cannot build our way out of the emerging “trilateral security dilemma” between the US, Russia, and China. “A nuclear arms race benefits no one,” she said. And yet the current state of affairs looks and sounds precisely like that: a high-tech, high-threat competition in which the US and its nuclear-armed adversaries are increasing production capacity, fielding new technologies, and overhauling or expanding arsenals—all without meaningful public discussion.

While most of the world looked away, the threat of a nuclear confrontation has surged to the highest level in decades. The days when the US and Russia jointly agreed to dramatically reduce their national stockpiles and cease nuclear testing are long gone. Relations between the US and China have devolved to their lowest point in years. Are we backsliding toward catastrophe?

“The vision of a world without nuclear weapons,” declared Congress’s bipartisan Strategic Posture Commission in its 2023 final report, “is more improbable now than ever.”

The detonation of a one-megaton nuclear weapon over New York City would begin with a blinding flash and a nightmarish pulse of heat and flame. People would be vaporized, turned to ash, burned alive, while the blast wave would demolish skyscrapers and rip buildings off their foundations. Glass, metal, and other debris would transform the air itself into a medium of death. Wind speeds could climb above 400 miles per hour. Fires ignited by the thermal pulse and broken gas lines would unleash a firestorm on the city. And a vast plume of radioactive fallout would envelop the area, particularly if the bomb were detonated at ground level. This fallout would spread with the prevailing winds, poisoning everything in its path, sickening the unlucky living. Millions would die. Social and economic order would collapse. Indeed, wrote the Nation journalist Jonathan Schell in The Fate of the Earth, his seminal book on nuclear weapons, “it is difficult to believe there would be appreciable survival of the people of the city after a megaton ground burst.”

Schell’s words, written more than 40 years ago, were intended to awaken American readers to the apocalyptic horrors of a nuclear attack on their largest city. Yet in the intervening decades, many have forgotten, or never learned, the lesson he and others tried so hard to teach. It was a lesson focused not only on the dangers Americans faced in an armed-to-the-teeth nuclear world but the dangers that this country—the only one to ever use nuclear weapons against another nation—posed to the rest of humanity. Now, as the world stumbles into a 21st-century arms race, it is imperative for the American public to understand its country’s arsenal—and to reckon with its leaders’ plans and policies for the nuclear future.

At the heart of these plans are the three prongs of the US arsenal—what is known as the nuclear triad, which consists of land-, air-, and sea-based weapons.

The first leg of this triad—the land-based system—can be found in the intercontinental ballistic missile fields of Montana, Nebraska, Colorado, North Dakota, and Wyoming. Scattered across these states, the fields are home to a constellation of underground silos that together house some 400 Minuteman III ICBMs—each armed with a thermonuclear warhead at least 20 times more powerful than the bomb that fell on Hiroshima in August 1945. (Collectively, in other words, they possess at least 8,000 times the destructive capacity of Little Boy.)

These land-based missiles are the most controversial prong of America’s nuclear triad. They exist, as the investigative journalist Annie Jacobsen writes in her searing new book, Nuclear War: A Scenario, “to kill millions of people on another side of the world.” And because they are stationary, with their locations known by ally and enemy alike, they are highly vulnerable to attack and thus are kept on heightened alert. Should US warning systems observe an incoming nuclear strike, these missiles could be launched within minutes. This “launch on warning” option means that the world is never more than a few minutes away from nuclear annihilation.

It also means that the communities living near these sites are at particular risk—and intentionally so. According to the bone-chilling logic of US military planners, America’s ICBM fields are meant to act as “a great sponge” that would absorb incoming missile fire in the case of a nuclear war, thereby diverting it from major US population centers. While there are significant holes in the logic of this “nuclear sponge” theory—any concerted attack on these ICBM fields would likely result in vast plumes of radioactive fallout spreading across the United States, far beyond the site of the initial nuclear blasts—this is cold comfort to the millions of people who live near the fields.

“According to my models, a concerted nuclear attack on the existing U.S. silo fields…would annihilate all life in the surrounding regions and contaminate fertile agricultural land for years,” wrote Sébastien Philippe, a Princeton University researcher, in an article published in Scientific American in December 2023.

Still, for all the danger they pose, these apocalyptic relics of the Cold War are not going anywhere, at least not anytime soon. In fact, America’s ICBM fields are currently undergoing a full facelift. The Air Force is refurbishing all 450 of its ICBM silos. The nuclear warheads that sit inside each missile will be replaced. And the Minuteman missiles themselves, for decades a staple of the US arsenal, will be retired in favor of a new ICBM called the Sentinel. Among other differences, the Sentinel will be longer and lighter than the Minuteman, will have more advanced guidance systems, and is designed to last into the 2070s.

In 2020, the Air Force awarded a sole-source contract to Northrop Grumman to develop the Sentinel. Based primarily at the company’s production facilities in Utah, the program has been beset by delays and cost overruns, which led to a recent decision by the Air Force to pause part of it. Last year, the Defense Department announced that the program will cost US taxpayers around $141 billion—tens of billions more than the price that was floated in a preliminary Pentagon estimate in 2016. These costs do not account for the development of the nuclear warheads that will go into each missile, which will have their own budget line numbering in the billions.

The other two prongs of the nuclear triad—sea- and air-based weapons—are also getting a makeover. The Navy is in the process of replacing its 14 Ohio-class nuclear submarines with 12 Columbia-class submarines, at a cost of some $130 billion. These long, sleek leviathans will be quieter than their predecessors. They will eventually be armed with upgraded Trident II ballistic missiles—shaped like cigars and stuffed with catastrophic explosive power—that have a range of more than 7,400 miles. Each missile can carry up to eight nuclear warheads. The largest of these is the 455-kiloton W88, which is undergoing a life-extension modernization program to be completed later this year. As they roll off the shipbuilding lines, the Columbia-class subs will sally forth from Naval Base Kitsap in Washington State and Naval Submarine Base Kings Bay in Georgia, slinking around the world undetected and virtually invincible, armed to the teeth with weapons that could wipe China or Russia, Iran or North Korea, off the map.

Up in the skies, meanwhile, the Air Force is developing a new strategic bomber called the B-21 Raider. Many of the details of the new bomber are classified, but according to researchers at the Federation of American Scientists, which closely tracks nuclear arsenals around the globe, “it is expected that the Air Force will procure at least 100 (possibly as many as 145) of the B-21, with the latest service costs estimated at approximately $203 billion for the entire 30-year operational program.”

The B-21 will be deployed at several bases around the country, including Ellsworth Air Force Base in South Dakota, Whiteman Air Force Base in Missouri, and Dyess Air Force Base in Texas. The bomber will be able to carry a new kind of air-launched nuclear cruise missile called the AGM-181 LRSO. It will also be equipped to carry two new gravity bombs—bombs that are simply dropped from the aircraft—called the B61-12 and B61-13; the latter will have an explosive yield (the amount of energy released) equivalent to 360 kilotons of TNT and will allow the president to home in on certain “hard and large-area military targets,” according to Hruby. (For reference, the explosive yield of Fat Man, the gravity bomb the US dropped on Nagasaki, was about 21 kilotons.) The production of these bombs, as well as that of numerous other components of the modernization program, is managed by the Department of Energy’s National Nuclear Security Administration, or NNSA, a semiautonomous civilian agency that stands at the center of America’s nuclear weapons complex.

These new missiles, submarines, bombs, and bombers are just a sampling of the vast program to remake America’s nuclear triad for the 21st century. The labs, factories, storage facilities, and bases behind this effort can be found all over the country. In New Mexico, Los Alamos National Laboratory is producing the plutonium pits needed for new nuclear warheads. In north Texas, the Pantex Plant is responsible for ongoing nuclear warhead assembly and disassembly activities. In the San Francisco Bay Area, the Lawrence Livermore National Lab is responsible for the design of the W87-1, the menacing warhead that will sit inside the Sentinel ICBM. This effort, the NNSA’s Hruby said in January, is “pushing all the limits of our infrastructure.”

Hruby’s speech, though delivered just a few months ago, was rooted in a set of relations and assumptions that no longer hold today. At the time, Biden, a son of the Cold War, was still in the White House, gamely overseeing two wars, with the world’s last major arms-control treaty soon to expire without a replacement. Now, with Donald Trump back in power, the burning questions are: What will this erratic man do? How will he approach the nuclear arms race of today?

The answers to these questions are both complicated and shifting, depending on which version of Trump—the trigger-happy strongman or the nuclear skeptic—is at the mic at any given moment. Several times since taking office, Trump has spoken of the need to engage in nuclear diplomacy, hinting at the possibility of a major arms treaty with Russia and China while also initiating talks with Iran (interspersed, to be sure, with fulsome threats against the country). On several occasions, he’s even suggested that we might do away with nuclear weapons; at least once, he’s criticized the United States’ huge nuclear modernization program: “There’s no reason for us to be building brand-new nuclear weapons—we already have so many,” he told reporters in the Oval Office in February. “You could destroy the world 50 times over, 100 times over. And here we are building new nuclear weapons, and they’re building nuclear weapons.”

Trump’s statements have offered a modicum of hope to arms-control experts and advocates. “I think it is too early to know whether these are performative statements or whether these are really serious and substantive proposals, but I am cautiously optimistic,” said Matt Korda, the associate director of the Nuclear Information Project at the Federation of American Scientists.

And yet, Korda warned, there are also reasons to be skeptical, since there are many “entrenched business and industry interests that will oppose a treaty that limits the scope of US nuclear modernization, and those folks have a lot of lobbying power.”

Indeed, America’s nuclear weapons complex is a self-replicating, bipartisan beast. Trump’s apparent hopes for a denuclearized world face the harsh reality that many powerful people and industries are enamored of these weapons, not least the senators and representatives from the states where ICBMs are manufactured and maintained. As the arms-control expert William Hartung wrote in a 2024 investigation for the Quincy Institute, “the nuclear weapons lobby is one of the most powerful forces in the military-industrial complex.” Together, he reported, 11 key weapons contractors involved in the Sentinel ICBM program employ some 275 lobbyists in Washington and spent $226 million over recent election cycles to influence members of the House and Senate Armed Services committees and other politicians and government institutions. Nukes are a big and thriving business.

With all that contractor cash flowing into campaign coffers, is it at all surprising that Congress is not eager to limit, much less do away with, the US nuclear arsenal? In its 2023 final report, the Congressional Commission on the Strategic Posture of the United States made numerous recommendations concerning America’s nuclear weapons policy. These recommendations were extremely hawkish: Given the rise of China as a nuclear peer and continued Russian military aggression, the commission urged the government to go beyond the current modernization program and, among other things, plan to install additional warheads on the nation’s ICBMs, increase the planned number of B-21 Raiders and the number of nuclear submarines, and consider placing ICBMs on road-mobile vehicles. “The size and composition of the nuclear force must account for the possibility of combined aggression from Russia and China,” the commission wrote in justifying its recommendations.

Trump’s own conservative allies may oppose arms-control negotiations as well. Project 2025—the Heritage Foundation’s blueprint for Trump’s second term—took an extremely aggressive stance on nuclear weapons, with Christopher Miller, the author of the section on the Defense Department, calling for the new administration to “reject proposals for nuclear disarmament that are contrary to the goal of bolstering deterrence.” Miller also encouraged the administration to build more modernized weapons systems, to bolster US missile defense programs, and to “restore readiness to test nuclear weapons” in Nevada—a radical move that would widely be seen as a serious escalation.

Trump will have to contend with such pressures if he wishes to pursue denuclearization. His own policies could also complicate any potential arms-control deal. The administration has aggressively touted a proposed “Golden Dome” missile defense system for the United States, a program similar to Israel’s Iron Dome. Such a defense system, if seriously pursued, could prove a major sticking point for any arms-control deal with Russia or China, which view US missile defense systems with deep suspicion, according to Korda.

“I don’t think [Trump] will pull off something meaningful,” said Jon Wolfsthal, who served as a director of nonproliferation on President Obama’s National Security Council. “I think most likely we will get performative arms control. He will sell the image of an agreement, but it won’t really reduce the number of nukes or enhance security or stability.” Wolfsthal added that he hopes Trump “does something meaningful, because it is possible, but history shows a poor track record.”

Meanwhile, the fundamental reality remains: The world at this moment is inundated with nuclear weapons, which pose an ongoing existential threat to humanity. A single thermonuclear weapon—and there are many thousands in the world today—could wipe any major urban center off the map in a matter of minutes. Even a relatively limited nuclear exchange—for example, in a conflict between India and Pakistan—could inject massive quantities of soot into the stratosphere, leading to global famine as temperatures plunge and food systems collapse. Such a scenario could kill more than 2 billion people, according to research published in Nature Food in 2022. A full-scale global nuclear conflict, like the one Jacobsen describes in Nuclear War: A Scenario, would very likely mean the end of our modern civilization and quite possibly the end of the human species itself.

At the beginning of the Cold War, when the United States and Russia were just starting out on their mad sprint to stockpile nuclear weapons, the muckraking journalist I.F. Stone denounced the prevailing mentality of the nuclear planners of that era. “Atomic war means national suicide,” he wrote. “The ultimate delusion of the atomic era is the notion that national suicide is a feasible means of defense; how apparently sensible and sane men could drift into such belief will astound future historians, if there are any.” The delusion persists to this day.