President Biden’s White House meeting with South Korean President Yoon Suk-Yeol underscored two facts that few citizens in both countries fully grasp. First, U.S. security policy toward allies still relies heavily on nuclear weapons. Second, hopes have long vanished that diplomatic talks might coax North Korea’s Communist regime to dismantle its atomic arsenal—and therefore, the threat of U.S. retaliation, including nuclear retaliation, is the most solid deterrent to war.
Even at their joint press conference on Wednesday, the two leaders shrouded these realities in diplomatic jargon. Biden and Yoon both spoke repeatedly of strengthening “extended deterrence” without quite defining the term. Basically, it means that the United States takes the basic concept of “deterrence”—if an enemy nukes us, we’ll nuke the enemy—and “extends” it to allies. In other words, if an enemy nukes an ally, we’ll nuke the enemy just as if he’d nuked us.
If North Korean troops were to invade South Korea with conventional arms, the U.S. would have plenty of assets to use to stave them off without resorting to nukes—25,000 armed forces members (in addition to 400,000 South Korean troops), the planes of the 7th Air Force, and the warships at Busan Naval Base, all loaded with precision-guided missiles, bombs, cyber gear, and a host of other weapons.
But over the decades, every American president has explicitly reserved the option to respond even to an invasion with nuclear weapons, if the stakes are very high and if a conventional defense alone can’t hold the line. Several presidents, including Barack Obama and Joe Biden, have considered adopting a “no first-use” policy. They have privately expressed doubts that any American president would be the first to use nuclear weapons in a war. But they have stopped short of declaring this view publicly for fear of alarming the allies, who would suddenly question the reliability of U.S. security guarantees and, in response, consider building their own nuclear arsenals—which could set off new rounds of regional tensions and arms races.
This is what seemed about to happen earlier this year. Yoon and a few South Korean security analysts mulled out loud that Seoul might need to build some atom bombs. North Korea, after all, was testing more ballistic missiles and enriching more uranium. When Donald Trump was president, he had talked about folding up the “nuclear umbrella” that had long protected South Korea and Japan, even pulling U.S. troops out of Asia (and, for good measure, withdrawing from the NATO alliance in Europe). They saw Trump preparing to run again in 2024. They heard many Republicans parroting his America-first rhetoric after regaining control of the House. South Koreans and other allies have made clear that they trust Biden to make good on U.S. pledges, but they have reasonable doubts about the next president. It makes sense for them to start at least pondering the idea of building their own deterrent.
Hence the meeting on Wednesday, which had been months in preparation. The upshot—expressed in a document heftily titled the “Washington Declaration,” signed by Biden and Yoon—pledges that the U.S. will make its extended deterrent more palpable. In exchange, South Korea will refrain from going nuclear itself.
The biggest new thing in this document is the establishment of a “Nuclear Consultative Group,” in which South Korean officials will have, as Biden put it, “a seat at the table” in discussions about nuclear war plans. The American president will remain the sole person to decide when, whether, and how to launch nuclear weapons. But South Korean officials will be let in on intelligence about North Korean nuclear threats—and on details of U.S. nuclear war plans. South Koreans will also take part in “tabletop” war games simulating various scenarios. South Korean fighter planes will fly alongside U.S. bombers in coordinated military exercises. And while U.S. nuclear weapons will not be restationed on South Korean soil (they were all removed in the early ’90s), U.S. submarines, armed with nuclear ballistic missiles, will pay occasional port calls, something that hasn’t been done since the 1990s.
The intended effect of all this is twofold. First, it makes the extended deterrent visible. It’s one thing for an American president to promise he’d launch ballistic missiles from South Dakota or the middle of the Pacific Ocean; it’s another for the South Korean president to see an American submarine loaded up with these missiles surfacing at a local naval base.
Second, and more important (if less dramatic), is that these moves institutionalize the extended deterrent. A future American president might want to scrap security commitments to South Korea or some other ally, but the scuttling will be harder if it requires breaking up a formal bilateral consultative group and a slew of relationships between the two countries’ military commands and intelligence bureaus. MAGA types might lambaste Biden’s move as an extended “deep state.” And yes, that is (sort of) the idea.
In exchange for getting a seat at the table, South Korea promises to keep abiding by the Non-Proliferation Treaty—i.e., to forgo any nuclear ambitions of its own. The idea of a South Korean bomb is no fantasy. In the 1970s, when U.S. troops were mired in Vietnam and Richard Nixon made his overtures to Mao’s China, Seoul’s leaders started doubting America’s reliability as an ally and did start a nuclear program. The program was suspended after the U.S. redoubled its assurances—and hasn’t gained real traction since.
Daniel Sneider, a lecturer in East Asian studies at Stanford University, told me on Wednesday that in recent interviews with officials and senior advisers in Seoul, nobody seriously advocated a South Korean A-bomb. Yoon’s main motive in advancing the idea publicly, Sneider said, “was to get the Americans’ attention.”
This new, harder edge in Washington–Seoul relations could not have emerged without recent changes in South Korean politics. Yoon’s predecessor, Moon Jae-in, was a keen advocate of warmer relations with the North, pursuing every slight opening as a possible prelude to a grand diplomatic settlement. Trump had his own fantasies along these lines, interpreting clever communiqués from North Korean dictator Kim Jong-un as “love letters.” By the time Yoon, a much more conservative figure, took office in 2022, these hopes had faded, negotiations (which never got off the ground) had folded, and it was clear that Kim had no intention of dismantling his nukes—or even revealing how many he has (probably 50 or so) or where they are.
The Washington Declaration states that Biden and Yoon “remain steadfast in their pursuit of dialogue and diplomacy with [North Korea], without preconditions, as a means to advance the shared goal of achieving the complete denuclearization of the Korean Peninsula.” But it’s clear that neither of them thinks this will lead anywhere. There is a U.S. emissary to North Korean talks named Sung Kim, but it is telling that he has a busy day-job as ambassador to Indonesia.
Pyongyang’s response to the White House meeting (which was followed by a lavish state dinner, only the second one that Biden has thrown as president) is bound to be grim. Prepare for a barrage of complaints from Kim’s minions about the American imperialists and their South Korean lackeys. But Kim brought this on himself. He stepped up his nuclear program when Seoul and Washington were ripe for détente. He had his reasons, many of them involving preserving his regime, whipping up war-scares to justify domestic oppression, and executing his own vision of deterrence: The nukes are all Kim has. He may be right that he’d face doom—from foreign invaders or his own rivals to power—if he agreed to junk them.
Meanwhile, there is nothing fundamentally new in the Biden-Yoon declaration. It’s an attempt to make more concrete the alliance between their two countries, now celebrating its 70th year. It doesn’t push Kim toward war; rather, it spells out very clearly, to one and all, what will happen if he wants to be pushed. That’s the theory, anyway.