The policy of every American president since Harry S. Truman has been to limit the proliferation of nuclear weapons.
They have not always been successful. The world’s most powerful weapons spread, with nine countries now possessing them. But no United States president has actively sought their further proliferation, as the belligerent policies of Donald Trump are now set to do.
In 2018, during his first term as president, Trump tore up the Iran nuclear deal, which had successfully placed limits on the enrichment of weapons-grade materials in exchange for sanctions relief.
Iran has since accelerated its nuclear weapons program. Estimates now put Iran within months or even weeks of producing several bombs.
A short time later, after a series of escalating threats, Trump suggested that North Korea had agreed to denuclearize. Talks ensued, but a deal never materialized.
In fact, Trump failed to stop, let alone roll back, North Korea’s ambitious nuclear weapons programs. North Korea is now said to possess at least 50 warheads as well as the means to deliver them.
No longer an ally
Under the second Trump administration, the world is facing a rapidly growing proliferation risk of a different kind, one that is found not only among the usual suspects in Iran and North Korea, but also among a long list of U.S. allies who once basked in American security guarantees.
Merely two months into Trump’s second term, America’s European allies have grown increasingly concerned that the U.S. is no longer a reliable ally.
That’s due to his suspension (and then reinstatement) of weapons transfers and intelligence sharing with Ukraine, an explicitly prioritized rapprochement with Russia, open denigration of its NATO allies, suggestions that the U.S. would not come to their defence if attacked, and his active and repeated threats to the sovereignty and territorial integrity of Canada, Greenland and Panama.
Against this backdrop, Trump’s guiding Project 2025 principles advocate escalating nuclear testing, breaking a long-held taboo.
Once protected by its nuclear umbrella, America’s closest allies are now threatened by it. Europe’s loss of confidence in the U.S. is so severe that finding alternatives has now become part of serious discussions in capitals across the continent. France and the United Kingdom are poised to fill the void by extending their nuclear deterrence to the likes of Germany and Poland.
The scene in Asia
But the risk of proliferation is greatest in East Asia. On the campaign trail in 2016, Trump mused that Japan and South Korea might need to develop nuclear weapons. “It’s only a matter of time,” he said.
That time is unfortunately now.
While Trump has been busy burning bridges in Europe and North America, his allies in East Asia — South Korea and Japan — have been watching the implosion of the U.S.-led international order in dismay. They have no alternative to the American nuclear umbrella but to build their own deterrent capabilities.
Polls now show that more than two-thirds of South Koreans support their country’s acquisition of nuclear weapons independent of the U.S. Key figures across the political spectrum as well as a growing chorus of academics and journalists have also openly floated the idea of nuclearization.
To address South Korea’s growing anxiety and check its nascent nuclear ambitions, the previous Joe Biden administration launched a bilateral initiative called Nuclear Consultative Group in 2023.
It established a regular mechanism between the two countries to discuss the state of the nuclear umbrella and perform joint defence exercises. This measure went a long way to quiet the voices calling for South Korean nuclearization — until Trump returned to the White House.
South Korea
Trump’s so-called America First foreign policy has given every reason for South Korea to once again question the reliability of U.S. security guarantees. If the Trump administration is willing to throw its oldest and closest allies in the North Atlantic under the bus, there is little reason for South Koreans to place their continued faith in the U.S.
As important as South Korea has been to an American grand strategy, it has always been a second-tier ally and its bilateral alliance with the U.S. was never as important as NATO or as special as the Canada-U.S. relationship. South Korea is much more vulnerable to abandonment, and it now appears to be expandable in the second Trump administration.
Going nuclear is not a question of means for South Korea. It has one of the most advanced civilian nuclear industries in the world, with 24 reactors in operation and more than enough scientific know-how to churn out weapons in a short time, estimated at six to 12 months.
The question has always been one of political will, the absence of which has rested on American security assurances. With the Trump administration actively demolishing security guarantees to its closest allies, South Korea may conclude that the only viable path to its continued existence in the post-American world is acquiring nuclear weapons.
Japan
South Korea’s nuclearization would likely lead to a domino effect, triggering a new wave of nuclear proliferation across the region. If South Korea makes a dash for the bomb, Japan will have no choice but to follow suit.
Japan has a full nuclear fuel cycle, including a uranium enrichment plant, spent-fuel reprocessing facilities, nine tons plutonium and 1.2 tons of enriched uranium that can be easily fashioned into thousands of nuclear bombs in as little as six months.
While the tragedies of Hiroshima and Nagasaki have long served as a guardrail against nuclearization in Japan, that moral taboo was sustained by a credible U.S. nuclear umbrella. And once the nuclear genie is out of the bottle, Taiwan will have every incentive to resurrect its earlier clandestine nuclear weapons program and seek its own deterrence capability.
Catastrophic dangers
While going nuclear may be individually rational for the East Asian countries, the collective outcome for the region and beyond is fraught with catastrophic risks.
The world is now grappling with the most dangerous collective action problem because the solution that has worked so well for decades — credible American security assurance — is eroding.
In upending the very international order that the U.S. established, the Trump administration is not merely chipping away at the global security architecture underpinned by myriad American security guarantees. It’s imploding the post-Second World War security order from within and the moral, political and institutional bulwark against nuclear proliferation.
In this predatory, zero-sum world of Trumpian foreign policy, putting America First necessarily means putting everyone else last — and, along the way, inadvertently fuelling nuclear proliferation.
The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.
This article was originally published on The Conversation. Read the original article.
