The defence chiefs of the United States and South Korea will hold talks on Tuesday in Seoul as Washington seeks to reassure a key Asian ally over its nuclear commitment amid growing threats from North Korea.

U.S. Defense Secretary Lloyd Austin arrived in Seoul on Monday and is set to meet South Korean Defence Minister Lee Jong-sup on Tuesday, following their annual security talks in November in Washington.

The latest meeting comes as South Korea pushes to bolster confidence in American extended deterrence – its military capability, especially nuclear forces, to deter attacks on its allies.

Nuclear-armed North Korea launched an unprecedented number of missiles last year, including intercontinental ballistic missiles (ICBMs) capable of reaching the U.S. mainland. Officials from both sides have also warned Pyongyang could be preparing for its first test of a nuclear device since 2017.

The North’s evolving threats had also revived calls from some politicians and experts in South Korea for bringing back U.S. tactical nuclear weapons or even developing its own nuclear programmes, though Seoul officials dismissed such a possibility.

Austin said his trip was aimed at deepening cooperation to tackle shared security challenges and reaffirm the U.S. extended deterrence commitment to South Korea is “ironclad” at a “time of heightened tension and provocation.”

“That’s why the United States and the ROK are taking clear, meaningful steps to modernise and strengthen our alliance,” Austin said in a special op-ed release on Tuesday by Yonhap news agency, referring to South Korea by the initials of its official name, the Republic of Korea.

“So our adversaries and competitors know that if they challenge one of us, they are challenging the U.S.-ROK alliance as a whole,” he added.

Lee has said the two countries will hold nuclear tabletop exercises in February under the scenario of North Korea’s nuclear attacks, as part of efforts to improve joint nuclear planning and implementation and boost information sharing.

Austin said the exercises are in line with the allies’ talks to expand extended deterrence activities and mechanisms on the peninsula and in the region.

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