Even after the Cold War, when the Soviet Union collapsed and the threat of nuclear destruction receded, the world’s nuclear states continued to follow the diplomatic and behavioral norms of that era. Years of inflammatory statements by North Korea and Russia, for example, were met with comparative calm from the United States, whose responses were carefully calibrated to deter aggression. Global leaders learned to look to the United States as a voice of nuclear reassurance.

Donald Trump’s inability or unwillingness to abide by these norms has revived the sense that Armageddon is once again within the realm of the possible. Tensions with North Korea have grown under his administration, and the danger of nuclear confrontation is now higher than at any time since the Cuban missile crisis. Part of this, of course, is due to North Korea’s pursuit of nuclear capabilities. But much of the blame lies with Trump himself.

Instead of working to de-escalate tensions, Trump has vowed to unleash “fire and fury” on the North Korean people and insulted Kim Jong Un, ridiculing him on the world stage as “Little Rocket Man.” Such reckless talk may simply be “Trump being Trump,” or part of his oft-stated strategy of “unpredictability” in negotiation. But predictability is essential to the stability that has protected us against nuclear annihilation for more than half a century. To North Korea’s leaders, Trump’s comments serve only to increase their sense of insecurity, fuel their desire to possess nuclear weapons, and decrease their hesitation about using them. This isn’t “winning”; it’s akin to lunacy.

Trump’s tweets and undisciplined remarks aren’t the only things setting the United States on a treacherous nuclear path, however. The Trump administration is currently preparing a new nuclear posture review, the government’s first since 2010. This comprehensive document outlines the nation’s nuclear capabilities and the conditions under which these weapons might be used. Current U.S. policy states that the president will consider using nuclear weapons only if another nuclear state launches a nuclear attack (or a massive conventional attack) against the United States or its allies—in other words, only in the most extreme circumstances. As the world’s last conventional superpower, the United States has every incentive to keep a fight from going nuclear, since such weaponry is the only counter to its conventional military dominance.

Trump, however, is reportedly pushing for the development of new nuclear weapons and delivery systems, and is expected to expand the circumstances under which they may be used. If this happens, the global nuclear balance may shift irrevocably. Rather than continuing the American role as the essential stabilizing force committed to preventing the proliferation of nuclear weapons, Trump could fuel a new nuclear arms race and increase the incentive for America’s enemies to strike first.


Trump’s expected overhaul of the country’s nuclear posture comes at a critical moment. The United States possesses the most fearsome nuclear arsenal on the planet: 4,000 weapons, 1,800 of which stand ready to strike anywhere in the world in 30 minutes or less. But these weapons, designed and built in the 1970s and 1980s, are old. The current “triad” of submarines, land-based missiles, and long-range bombers is being replaced so that the United States can maintain its nuclear readiness.

Barack Obama began modernizing the nuclear arsenal before he left office, an effort that will cost an estimated $1.24 trillion over the next three decades. It might seem surprising to some that Obama would call for such changes. In 2009, he pledged to seek “a world without nuclear weapons,” and in 2010 he negotiated an arms treaty with Russia that required both countries to reduce significantly the size of their nuclear arsenals. Certainly, the United States does not need so many nuclear weapons. The Joint Chiefs of Staff concluded in 2013 that the United States could safely reduce its nuclear arsenal by an additional one-third and still meet its military needs.

But Obama was also committed to ensuring that the United States can still fend off nuclear attacks and prevent other countries from pursuing their own nuclear programs. His policy attempted to strike a balance—restricting the role of nuclear weapons while maintaining America’s deterrence capability. Obama supported the goal of making the “sole purpose” of nuclear weapons to deter a nuclear attack, and also considered a “no first strike” rule—though ultimately he did not put such a limit in place.

Trump clearly has no affection for Obama’s pragmatic approach. “Why have them if we can’t use them?” Trump reportedly asked one of his foreign policy advisers during the campaign. Last summer, he also reportedly told military leaders that he wanted a tenfold increase in the nuclear stockpile, returning to the highest levels of the Cold War. And he is apparently considering the development of smaller, more “tactical” nuclear bombs.

Some nuclear strategists have speculated that the U.S. nuclear arsenal is so powerful that the United States would never use it. The loss of life and damage to the planet would be too great. They point to Russia’s threats to use nuclear weapons against NATO as a sign that Moscow does not view nuclear retaliation as credible. Smaller bombs, the thinking goes, would send a clear signal to Russia that its use of nuclear weapons would be met with an appropriate response.

There is no evidence that Russian officials think this way, however. Russia’s statements about using nuclear weapons should be viewed as tough talk to mask its military inferiority, rather than as a sign that it doubts America’s resolve. Building smaller bombs won’t keep other nuclear powers in check. But it could encourage the United States to use nuclear weapons, even if doing so is militarily and politically unnecessary. It would also give Russia a pass on its own threats of first use, instead of making it increasingly a pariah for its strategy of escalation.

Worse yet, unlike Obama, whose policies limited the circumstances under which nuclear weapons could be justified, Trump is likely to expand the rationale for nuclear war—in response to an attack on critical U.S. infrastructure, for example, or a large-scale cyberattack. And he has signaled that he may once again consider using nuclear weapons against nonnuclear states. All of this, combined with Trump’s bellicose, and at times unhinged, statements, ratchets up tensions around the world and makes it easier for other countries—Russia, Pakistan, and even North Korea—to threaten a nuclear response to nonnuclear scenarios.


Can Trump be contained, and if so, by whom? As tensions with North Korea have increased, lawmakers in Congress are considering legislation to restrict the president’s ability to order a nuclear first strike. One bill would require Congress to declare war before nuclear weapons can be used. Another currently in the works would make “no first use” the official policy of the United States. Senator Bob Corker has energized the debate with his comments that Trump’s recklessness could lead to “World War III” and that only the secretary of state, the secretary of defense, and the White House chief of staff stand between the United States and “chaos.”

In today’s polarized environment, however—in which only retiring lawmakers seem to say what everyone else is thinking about the dangers posed by Trump’s judgment and temperament—these bills are going nowhere. This is a shame, since it makes no sense for any president, Democrat or Republican, to have the ability to use nuclear weapons against a country that has not attacked the United States or its allies with such weapons first.

Even if Trump cannot be constrained politically, he may find himself hemmed in financially. The $1.24 trillion price tag to modernize the nuclear arsenal already exceeds initial estimates and is expected to keep growing. On its own, the nuclear bill is something the United States can afford, even if it is extravagant and increasingly unnecessary. But the financial demands come just as the bills for other major programs—the new F-35 fighter jet, in-air refueling tankers, and Navy combat ships—are coming due. Trump has just asked for billions more to expand missile defenses against North Korea—despite the evidence that America’s missile defense capabilities are much less reliable than most people believe. The government cannot possibly meet all of these financial obligations. Regardless of what Trump says he wants, priorities will have to be set and choices made.

Whatever proves to be the fiscal reality, Trump’s rhetoric is opening the door to a new era of instability. For 70 years, through the Cold War and after, nuclear powers acted according to a prescribed set of rules and codes of conduct. Trump has disrupted all of that—greatly increasing the chances of miscalculation or escalation. And the crisis will not end when Trump leaves the White House. Some of the new weapons and delivery systems that Trump wants will take years to develop, meaning that the next president will have even more options on the table—and more threats to face.

The United States has spent the last three decades free from the fear of nuclear annihilation, thanks in large part to a rational combination of threats, diplomacy, and reassurance. Trump’s rejection of these norms creates a new nuclear shadow that may linger long after he departs.