The US and South Korea are actively discussing closer collaboration in the deployment and potential use of nuclear weapons, which is part of the far broader US-led military build-up throughout the region. While nominally directed against North Korea, US war preparations including with South Korea are above all aimed at China.

In an interview in the Chosun Ilbo newspaper on Monday, South Korea’s right-wing president, Yoon Suk Yeol, said the discussions had focussed on joint planning and exercises with American nuclear forces. He described the arrangements being discussed as being “as good as nuclear-sharing”—a phrase, he said, that Washington was uncomfortable with.

Yoon explained: “The nuclear weapons belong to the United States, but South Korea and the United States should jointly share information, plan, and train together. The United States also feels quite positively about this idea.”

When asked at the White House whether joint nuclear military exercises with South Korea were being planned, President Biden flatly declared “no” and made no further comment. However, subsequent comments by American officials make clear that the closer integration of South Korea into US preparations for nuclear war is indeed under way.

A senior US administration official told Reuters that while regular nuclear exercises with South Korea would be “extremely difficult” as it is not a nuclear power, the two countries are discussing other means for collaborating. The talks were instigated by Biden and Yoon after meeting in Cambodia in November to address the North Korean threat.

“This is going to be done through a variety of ways, including as President Yoon said, through enhanced information sharing, joint planning and expanding the range of contingencies that we plan for, as well as training, and with the idea eventually leading up to a tabletop exercise,” the official explained.

The plans, as President Yoon’s comments would indicate, are well advanced. While a date for the tabletop or simulation exercises has not been finalised, the official said they would take place “in the not-too-distant future” and cover scenarios including nuclear situations.

In a statement issued on Tuesday, Yoon’s press spokesperson, Kim Eun-hye, confirmed that Seoul and Washington “are discussing an intel-sharing, a joint planning and subsequent joint execution plans over the management of US nuclear assets in response to North Korea's nuclear [threats].”

The discussions mark a significant escalation in the preparations for nuclear war. While South Korea, a US military ally, was protected by the so-called nuclear umbrella or what is known as “extended deterrence,” Yoon is pushing for a greater South Korean say in the use of nuclear weapons.

In his interview, Yoon declared: “What we call ‘extended deterrence’ means that the United States will take care of everything, so South Korea should not worry about it… But now, it is difficult to convince our people with just this idea.”

Yoon has adopted a more aggressive stance towards North Korea than the previous Democrat president, Moon Jae-in. Prior to assuming the presidency last May, Yoon called for the return of US tactical nuclear weapons to South Korea or an arrangement like that with NATO allies, under which South Koreans would be trained to launch US nuclear weapons in a conflict.

Throughout much of the Cold War, the US had hundreds of tactical nuclear weapons in South Korea supposedly to counter a North Korean invasion. The number peaked at 950 during the mid-1960s before declining. In 1991, amid the moves to dissolve the Soviet Union, US President George H.W. Bush announced the return of all tactical nuclear weapons to the US, including those that remained in South Korea.

While Yoon has not publicly repeated his proposals as president, there have already been significant steps to a greater US nuclear presence in South Korea. In a joint press conference last November, US Defense Secretary Lloyd Austin and South Korean Defense Minister Lee Jong-seop announced plans for the de facto permanent stationing of US nuclear-capable assets in South Korea for the first time since 1991.

While Austin described the deployments as rotations, Lee said the US would send “strategic assets to the level equivalent to constant deployment through increasing the frequency and intensity of strategic asset deployment in and around the Korean peninsula.” The two countries underlined the move by flying two B-1B strategic bombers, accompanied by South Korean and US fighters, over the Korean peninsula for the first time since 2017.

As far as Washington is concerned, the North Korean “threat” is a convenient pretext as its nuclear planning is primarily focussed on war with China. Strategically located close to the Chinese mainland, South Korea is deeply integrated into the US strategy for such a conflict. Not only does it house key US military bases and some 28,500 military personnel but it also has a key anti-ballistic missile system—a recently upgraded Terminal High Altitude Area Defense (THAAD) system—critical in any nuclear conflict.

The US is boosting its nuclear weapons capacity throughout the region with the announcement last year that it will effectively station nuclear-capable B-52 bombers at the Tindal air force base in Northern Australia. At the same time, prior to his assassination last July, former Japanese prime minister Shinzo Abe initiated a discussion in ruling circles about stationing US nuclear weapons in Japan, despite enormous popular opposition to such a move.

The Biden administration has already taken steps to strengthen its military alliances in the Indo-Pacific by kickstarting the Quadrilateral Security Dialogue or “Quad” with Japan, Australia and India as well as initiating the AUKUS pact with Australia and the United Kingdom, which, in particular, will arm Australia with nuclear-powered attack submarines. At the same time, it has sought to strengthen intelligence sharing between South Korea and Japan, essential in any nuclear conflict.

Broader “nuclear sharing” is also being discussed in US strategic think tanks. A comment published last August by the US Council for Foreign Relations highlighted a proposal to establish an Asian Nuclear Planning Group, “mirroring the format of the NATO Nuclear Planning Group, that would provide a platform for South Korea, Japan, and Australia to discuss policies regarding US nuclear forces and the US nuclear planning process.”

What is underway not just in South Korea are high-level discussions to integrate US allies throughout the region with the US military as preparations accelerate for a potentially catastrophic war with China that would inevitably involve the use of nuclear weapons.