Nuclear tensions on the Korean peninsula are accelerating dramatically

Ivo Daalder, former U.S. ambassador to NATO, is president of the Chicago Council on Global Affairs and host of the weekly podcast “World Review with Ivo Daalder.”
South Korean President Yoon Suk Yeol has sent a nuclear shot across the bow, declaring earlier this month that if problems get worse, “our country will introduce tactical nuclear weapons or build them on our own.”
And his remark should send alarm bells ringing in Washington and allied capitals across Europe and Asia.
Yoon’s statement — which he emphasized didn’t constitute official policy — came in response to a highly belligerent speech by North Korean strongman Kim Jong Un in December. Already following a year in which North Korea tested more missiles of all ranges than in any previous 12-month period, Kim announced that Pyongyang would start “mass-production of tactical nuclear weapons,” leading to “an exponential increase of the country’s nuclear arsenal.” And few would be surprised if he decided to conduct a seventh nuclear weapons test this year.
Whether formally recognized or not, the fact is that North Korea is a nuclear-armed state with dozens of weapons and the ability to launch them over short, medium and long ranges — including likely against the continental United States.
Diplomacy won’t curtail its nuclear potential. Over the last three decades, the U.S. has led multiple efforts — both in concert with other countries and through bilateral summit diplomacy — to convince a succession of North Korean leaders to implement a 1991 pledge to denuclearize the peninsula. But there’s been no serious diplomatic engagement with Pyongyang since the failed meeting held between Kim and former U.S. President Donald Trump four years ago.
Instead, nuclear tensions on the peninsula are accelerating dramatically — with Yoon now ratcheting them up a bit more.
To be sure, the South Korean president wasn’t suggesting he favored a nuclear arms race —though he did warn, “we can have our own nuclear weapons pretty quickly, given our scientific and technological capabilities.” Rather, given the growing North Korean nuclear missile threat, Yoon was sending a message to Washington that Seoul is increasingly worried about the reliability of the U.S.’s security commitment.
Part of the worry stems from the shock of the Trump years, during which the former U.S. president repeatedly questioned the need to maintain troops in Korea, or even keeping the security alliance itself. But part of it also comes from the changed security environment — not least the reality that the U.S. is now vulnerable to nuclear attack from North Korea.
And that vulnerability raises a question, long familiar to European allies, about whether the U.S. would be willing to sacrifice Seattle to save Seoul when faced with the prospect of nuclear retaliation.
Thus, in his statement, Yoon made clear that the best way to ensure South Korea’s security was to bolster its alliance with the U.S., and prevent war in the first place. And one way to do so, the South Korean president suggested, would be to return the U.S. tactical nuclear weapons Washington had unilaterally withdrawn from South Korea in 1991. Failing that, however, he held open the possibility of Korea developing its own nuclear deterrent.
Washington is acutely aware of the dilemma this might cause. One reason it embraced defense alliances and committed to extending a nuclear umbrella to allies in Europe and Asia in the first place, was to persuade them to rely on American nuclear weapons for their defense rather than develop their own.
And this strategy has been incredibly successful.
In 1963, then-U.S. President John F. Kennedy warned of a “world in which 15 or 20 or 25 nations may have these weapons” within a decade, expressing the widely held belief that proliferation was likely, if not inevitable. Thankfully, that didn’t happen, and in the nearly 60 years since, just five other countries — China, Israel, India, Pakistan and North Korea — have become nuclear powers. America’s steadfast commitment to maintaining the nuclear umbrella for its allies was a major reason why.
But Yoon’s nuclear warning sends an important message to Washington — and allied capitals in general: As the security environment becomes more challenging, the need to adapt alliances increases as well.
We’ve just witnessed two important examples of this. Following Russia’s invasion of Ukraine, NATO responded by bolstering its defense and deterrence posture in Eastern Europe, approving the membership applications of Finland and Sweden and significantly increasing its long-term defense spending commitments.
And earlier this month in Washington, U.S. President Joe Biden and Japanese Prime Minister Fumio Kishida announced key steps to bolster the U.S.-Japan security alliance, including closer consultation on the U.S. nuclear posture, as well as the redeployment and reconfiguration of U.S. Marines in Japan. In return, Tokyo committed to doubling its defense spending over the next five years.
In the nuclear age, security alliances are nuclear alliances — a reality ignored for much too long, not least by European and Asian allies since the Cold War nuclear confrontation ended. Today, Russia’s nuclear saber rattling and North Korea’s commitment to exponentially increasing in its nuclear potential should remind everyone of this reality.
That was the real meaning of Yoon’s nuclear warning.