The US is significantly stepping up its commitment to use its nuclear arsenal to defend South Korea, as it seeks to reassure Seoul about the strength of their alliance in the face of threats from North Korea.
President Joe Biden and his South Korean counterpart Yoon Suk Yeol said on Wednesday that the US military would deploy more nuclear-capable bombers and other strategic assets on temporary missions to South Korea to send a clear message to Pyongyang about deterrence.
The two countries, which celebrated the 70th anniversary of their alliance last year, also announced a new bilateral nuclear consultative group to give Seoul more insight and input into US war planning.
Biden and Yoon, who is on a state visit to the US, released a “Washington declaration”, including a commitment from South Korea not to develop its own nuclear weapons.
Speaking at a press conference with Yoon, Biden said the US-South Korea mutual defence treaty was “ironclad”.
“That includes our commitment to extended deterrence,” Biden said, using the military term for the US nuclear umbrella that helps protect its allies.
Biden said any North Korean nuclear attack against the US or its allies would result in “the end” of the regime in Pyongyang. Yoon welcomed the creation of the new consultative group, saying that in the event of a North Korean nuclear attack, the two countries had agreed “to respond swiftly, overwhelmingly and decisively using the full force of the alliance, including the United States’ nuclear weapons”.
The rhetoric and new military deployments are designed not only to reassure the South Korean public that Washington will defend its ally but also to ensure that Seoul does not build atomic weapons, which US officials worry would spark a dangerous nuclear arms race in Asia.
“We intend to take steps to make our deterrence more visible through the regular deployment of strategic [nuclear] assets, including a US nuclear ballistic submarine visit to South Korea, which has not happened since the early 1980s,” said one senior US official.
The official added that the allies would boost training to enhance deterrence and work towards “better integrating Republic of Korean conventional assets into our strategic planning”. A second official said the increased visibility would include more visits by aircraft carriers.
The second official said the nuclear consultative group was inspired by a similar arrangement Washington had with Nato during the cold war, but while Nato has tactical nuclear weapons in Europe, the US has no nuclear weapons in South Korea. “I’ll be crystal clear, there is no vision of returning US tactical or any other kind of nuclear weapon to the Korean peninsula,” the official added.
Zack Cooper, an Asia security expert at the American Enterprise Institute, said the move would ensure that South Korea did not try to develop nuclear weapons, while giving Seoul the assurances it had repeatedly sought from the US.
“This is a smart effort to proactively address a growing risk to the . . . alliance: Seoul’s dalliance with the idea of acquiring its own independent nuclear capabilities,” said Cooper.
“It is only natural that experts and the public in South Korea would want to bolster deterrence capabilities. After all, North Korea continues to expand and modernise its nuclear forces while Russia levies nuclear threats and China engages in a massive nuclear build-up.”
But there are doubts, including whether the agreement can hold if Donald Trump wins the US presidential election in 2024.
Go Myong-hyun, a senior fellow at the Asan Institute for Policy Studies in Seoul, said that the level of reassurance offered to Seoul by Washington would depend on the “precise agenda” of the new consultation group.
“The important thing for the South Koreans is to be able to get greater insight and input into US thinking on nuclear issues . . . specifically nuclear use scenarios in the event of a war with North Korea,” said Go, who added that the visible visit of a nuclear-armed submarine is “definitely a win” for the South Korean side.
Anxiety in Seoul has grown as North Korea continues to develop its nuclear weapons programme. Last year, Pyongyang adopted a new nuclear doctrine allowing pre-emptive strikes in a wide range of scenarios, including when the country or the government was attacked by conventional forces.
South Korean leaders — including Yoon himself — have openly speculated that Seoul could one day pursue its own nuclear deterrent, a move strongly opposed by the US.
Go said this reflected longstanding fears that North Korea’s nuclear capabilities may already be sufficient to deter the US from intervening in any conflict on Seoul’s behalf.
“There has always been a fear in South Korea of US abandonment,” said Go. “The Biden administration will succeed in reassuring the Koreans for the time being, but the underlying dilemma has not gone away.”