U.S. and South Korea Agree to Cooperate on Nuclear Weapons

WASHINGTON — The United States will give South Korea a central role for the first time in strategic planning for the use of nuclear weapons in any conflict with North Korea, in return for an agreement that Seoul will not pursue its own nuclear weapons arsenal, American officials said.

The agreement, which the two sides are calling the Washington Declaration, is a centerpiece of this week’s state visit by President Yoon Suk Yeol of South Korea, who will appear with President Biden at the White House on Wednesday.

The new cooperation is closely modeled on how NATO nations plan for possible nuclear conflict, but the American president will retain the sole authority to decide whether to employ a nuclear weapon. While the United States has never formally adopted a “no first use” policy, officials said such a decision would almost certainly come only after the North itself used a nuclear weapon against South Korea.

On Wednesday morning, John F. Kirby, a spokesman for the National Security Council, said, “I would caution anyone from thinking that there was new focus on the centrality of nuclear weapons,” despite the wording of the new declaration. “We have treaty commitments to the Republic on the peninsula,” he said, using the shorthand for the Republic of Korea, and “we want to make sure we have as many options as possible.”

The accord is notable for several reasons. First, it is intended to provide assurance to the South Korean public, where pollsters have found consistent majorities in favor of building an independent South Korean nuclear force. President Yoon himself mused openly about that option early this year, though his government quickly walked the statement back. He also raised the possibility of reintroducing American tactical nuclear weapons to South Korea, a step that his government has said in recent weeks it is no longer pursuing.

The United States withdrew its last nuclear weapons from Korea in 1991, under the George H.W. Bush administration.

But the second reason it is important is one the Biden administration is saying little about: It edges toward reversing the commitment, going back to the Obama administration, to reduce the role of nuclear weapons in American defense strategy. For years, the United States has been improving its non-nuclear strike options, improving the precision and power of conventional weapons that could reach any target in the world in about an hour.

But the South is looking for greater assurance of “extended deterrence,” the concept that the United States will seek to deter a North Korean nuclear strike on the South with a nuclear response — even if that risks a North Korean strike on an American city.

South Korea is a signatory to the Nuclear Nonproliferation Treaty, which prohibits it from obtaining nuclear weapons. So the commitment not to build its own weapons is not new. But nations can withdraw from the treaty, simply by providing notice to the United Nations. Only one nation has done so: North Korea, in the early 1990s. Three countries have not signed the treaty and have developed nuclear weapons: Israel, India and Pakistan.