The United States should redeploy tactical nuclear weapons in South Korea to send a clear message to North Korea and alleviate growing calls in the South for developing its own bombs, former US National Security Adviser John Bolton said on Tuesday.

Iran PressAmerica: Bolton's remarks came as South Korean President Yoon Suk Yeol is in Washington for a summit with US President Joe Biden, during which they are expected to discuss ways to improve confidence in US extended deterrence - the American nuclear umbrella protecting its allies.

As North Korea races to perfect its ability to strike the US with a nuclear missile, Yoon faces questions about South Korea's security reliance on the US, with some senior members of Yoon's party calling for Seoul to spin up its own nuclear programs.

Bolton said re-stationing US tactical nuclear weapons would help reassure South Koreans while sending a warning to Pyongyang.

"Having tactical nuclear weapons back on the peninsula would be clear evidence of our resolve and determination to deter North Korea," he told Reuters on the sidelines of a forum hosted by the Asan Institute for Policy Studies in Seoul.

"Redeploying the tactical weapons does not preclude South Korea from getting its own capability, but it may give us some time to think about whether we really want to do that," he added.

The United States deployed tactical nuclear weapons to South Korea in 1958 and pulled them out in 1991. It has since vowed to use all of America's capabilities to defend its key Asian ally.

Yoon had said during the election campaign that he would ask the United States to bring nuclear weapons back to South Korea if necessary but backtracked after taking office in May. His defense minister, Lee Jong-sup, said in November that Seoul was not considering such a move.

In an interview with Reuters last week, Yoon said that developing nuclear weapons violates the global nuclear non-proliferation treaty, but that he was working to boost Seoul's role in US extended deterrence.