The world’s most important nuclear weapons treaty is in grave danger. Judging from former President Donald Trump’s record in office, as well as his and key associates’ rhetoric since then, a second term could kill it.
For almost 60 years, U.S. presidents of both parties have agreed that the United States should work to stop the spread of nuclear weapons. Trump has signaled he’s not so sure – and his policies may unravel the best mechanism the world has to prevent nuclear proliferation.
Nuclear weapons are the most devastating armaments humankind has ever developed. It is therefore surprising that, even though dozens of countries have the technological ability to develop them, almost all choose not to. This is no accident.
The Fading Bipartisan Legacy of Nonproliferation
In the early 1960s, President John F. Kennedy openly worried that the world was close to a scenario in which 20 or more countries would obtain nuclear weapons. Members of his administration sought to bring the world together to stop the spread, or proliferation, of nuclear weapons through an international treaty. Their efforts culminated in the 1968 Treaty on the Non-Proliferation of Nuclear Weapons (the NPT). At the time, six countries likely possessed nuclear weapons. Since the NPT entered into force, only three more countries – India, Pakistan, and North Korea – have acquired such arms. That track record far exceeded Kennedy’s predictions. But it would be dangerous to take it for granted.
The success of the NPT has required bipartisan vigilance. Multiple administrations across the 1970s and 80s worked to disrupt Taiwan’s nuclear program. President Gerald Ford exerted significant pressure on South Korea to dissuade it from pursuing a nuclear weapon. Presidents George H.W. Bush and Bill Clinton successfully convinced Ukraine to give up the nuclear weapons on its territory (even though Ukraine never had full operational control of them). And President Obama sponsored numerous Nuclear Security Summits, which helped secure vast quantities of nuclear material. He also brought the world together to pressure Iran to stop short of developing a nuclear weapons capability.
Remarkably, the White House has often paid as much attention to stopping proliferation among America’s friends as among its adversaries. This has been made possible by the so-called “nuclear umbrella,” an arrangement under which U.S. allies and partners refrain from developing their own nuclear weapons programs in exchange for assurances that the United States would use its own military forces to protect them in a conflict.
But Trump has never believed the nuclear umbrella is worth the costs.
Trump’s Record on Nuclear Proliferation
Trump is a known skeptic of U.S. alliances, and his skepticism has long had a nuclear component. As a candidate in 2016, Trump argued the United States should throw away the idea of providing a nuclear umbrella. He maintained that countries like Japan should develop nuclear weapons because “it’s going to happen anyway.” He also said, “Wouldn’t you rather, in a certain sense, have Japan have nuclear weapons when North Korea has nuclear weapons?”
Trump continued this outright hostility to the nuclear nonproliferation regime into his presidency. He exacerbated nonproliferation pressures by denigrating allies, abandoning nuclear agreements, and undermining U.S. commitments under the NPT.
To an extent he only recently acknowledged, Trump pushed U.S. allies to either pay more for their own defense or else he would essentially “encourage” Russia to invade them, too. His administration also withdrew from the 2015 Iran nuclear deal and failed to reach an agreement with North Korea on limiting its nuclear program. Additionally, Trump indirectly weakened nonproliferation by failing to live up to the spirit of the NPT’s requirement that nuclear weapons States eventually give up their nuclear arsenals. As president, he refused to extend the New START agreement with Russia, the last remaining legal limit on the world’s largest two nuclear stockpiles, leaving it to the Biden-Harris administration to sign the one-time extension in the chaotic 16 days between their inauguration and the treaty’s extension deadline.
These actions eroded faith in the U.S. nuclear umbrella and undercut international efforts to uphold the NPT. The fallout from Trump’s first term is ongoing, with U.S. allies worldwide distancing themselves from their nonproliferation commitments. In South Korea, public interest in pursuing nuclear weapons has increased dramatically, with 71 percent of the country now in favor of developing its own nuclear weapons. South Korean President Yoon Suk Yeol even campaigned on the issue, saying he was open to an indigenous nuclear weapons program. His new defense minister expressed similar views, arguing South Korea had “no survival or future” without its own nuclear deterrent. In Europe, Germany is now considering nuclear weapons, with officials in Berlin already seeking to Trump-proof European nuclear deterrence by coordinating with their counterparts in Paris and London.
Trump’s Second Term
While Trump’s antipathy to alliances weakened the NPT in his first term, the same sentiment stands to damage the treaty irrevocably in his second.
In Europe, Trump could very well make good on his threat to withdraw from NATO, something he and his campaign have repeatedly suggested he wants to do. His hostility towards U.S. support for Ukraine is well-known, but the consequences will extend far beyond Ukraine and the immediate neighborhood. The nonproliferation regime will likely fray even further if Ukraine fails to recover a substantial part of its territory: Rightly or wrongly, countries will conclude that they need their own nuclear deterrents. They will choose to bet on themselves rather than rely on the U.S. umbrella.
In East Asia, Trump could withdraw U.S. troops from South Korea, something he wanted to do in his first term and has flirted with doing in his second. With the current military cooperation agreement between the two countries set to expire next year, a re-elected President Trump would likely try to threaten South Korea with a U.S. troop withdrawal, driving proliferation pressure even higher in that country.
And in the Middle East, Trump could spark a nuclear arms race. Given his withdrawal from the Iran nuclear deal, Tehran is now drastically closer to producing the fissile material necessary for a nuclear weapon. As Iran’s nuclear program advances, the risk of proliferation by Saudi Arabia will increase; the Saudi leadership has repeatedly promised to violate its nonproliferation pledge if Iran gets a nuclear weapon. Rather than oppose such an outcome, Trump’s administration shared sensitive nuclear information with the Saudis. Moreover, his complex personal and business ties to the Kingdom suggest he would be unable or unwilling to ensure that any future nuclear cooperation comes with adequate safeguards to prevent proliferation.
Next President Faces Bleak Nuclear Landscape
Each of these possibilities is all the more concerning given the bleak nuclear landscape the next president will inherit.
Vladimir Putin’s illegal and reckless invasion of Ukraine and his legally invalid abrogation of Russia’s New START commitments have already done grave damage to nonproliferation over the last two-and-a-half years. With New START set to expire in 2026, this time with no option for an extension, the situation is set to go from bad to worse. This dismal likelihood would weaken the moral and legal case for other countries to maintain their own NPT commitments. In such an environment, the Project 2025 plan, written by Trump’s closest allies and former aides, increases U.S. reliance on nuclear weapons and would likely weaken that moral and legal case even further, especially as close Trump advisers openly support a return to nuclear testing for the first time since 1992.
In a second term, Trump’s plans, especially when combined with his longstanding antipathy for the U.S. alliance system, could even have repercussions beyond the NPT itself. As others have pointed out, nuclear norms are interrelated. This means that if the nonproliferation norm unravels, it is likely that other norms, including against nuclear testing or even nuclear use, will diminish as well. In such a climate, Trump’s disengagement with, if not open acceptance of, proliferation could prove fatal not just to the NPT, but to the entire international nuclear regime.
In contrast, Vice President Harris has a track record of defending nuclear agreements and the alliances that strengthen them. As a presidential candidate in the 2020 election, Harris supported a verifiable, reversible, diplomatic agreement with North Korea to roll back its nuclear program. She also defended nonproliferation agreements like the Iran nuclear deal and supported the one-time extension of New START. As vice president, she has been an outspoken supporter of NATO and other traditional U.S. alliances. And despite all the understandable anger at the Kremlin over the war in Ukraine, the Biden-Harris administration has repeatedly kept open the possibility of negotiating with Russia on nuclear weapons.
While the Biden-Harris administration’s nuclear policy has disappointed the nonproliferation community at times, there is no doubt that Harris represents the successful and bipartisan tradition of maintaining U.S. alliances to deter nuclear proliferation.
Conclusion
Presidents of both parties have worked hard to avert Kennedy’s ominous vision of a world rife with dozens of competing nuclear powers. Through hard work, they constructed a mostly effective — yet always fragile — international system to contain the world’s most powerful weapons. Trump’s alliance skepticism could collapse that system.