Seoul Mayor Oh Se-hoon, in an exclusive interview with Reuters, added new fuel to a growing debate over how South Korea should arm itself as the North races to perfect its ability to strike the South with tactical nuclear weapons

South Korea should build nuclear weapons to bolster its defences against North Korea, even if it means risking international repercussions, according to the mayor of the country's capital city, arguing that the country cannot be bound by the goal of denuclearisation.

Seoul Mayor Oh Se-hoon, in an exclusive interview with Reuters, added new fuel to a growing debate over how South Korea should arm itself as the North races to perfect its ability to strike the South with tactical nuclear weapons.

“North Korea has almost succeeded in miniaturising and lightening tactical nuclear weapons, and it has secured at least dozens of warheads,” Oh said. “We've reached a point where it's difficult to persuade people with logic that we should stop developing nuclear weapons and focus on denuclearisation,” he added.

He has previously raised the issue, stating in February that the South should keep the nuclear option open. But his new remarks are his most forceful yet.

Oh, a conservative member of President Yoon Suk Yeol's People Power Party, is one of the most prominent officials to advocate for a South Korean nuclear weapons programme.

He is widely regarded as a possible presidential candidate in 2027. As mayor, he is in charge of Seoul's annual civil defence drills as well as an integrated security mechanism designed to protect a metropolitan area that is home to nearly half of the country's 51 million people.

Amid North Korean military advances and doubts about the United States' commitment or ability to protect the South, a growing number of senior South Korean officials have raised the prospect of developing nuclear weapons or redeploying American tactical nuclear bombs and missiles that were withdrawn from the Korean Peninsula in the 1990s.

Yoon proposed US redeployment as a candidate, but his administration has since stated that it remains committed to denuclearisation and would strengthen combined conventional defences with the US.

Surveys, on the other hand, show unprecedented levels of public support in South Korea for the previously unthinkable concept of a homegrown nuclear arsenal.

In a Data Research poll released on 1 March, more than 70 per cent of South Koreans supported the development of nuclear weapons, with 27 per cent opposed, and 59 per cent said North Korea would most likely use nuclear weapons if war broke out on the peninsula.

The Ukraine crisis, according to Oh, has solidified his belief that denuclearisation has lost its appeal and that nuclear weapons would be the most effective deterrent against the North.

“Russia freely violates Ukrainian airspace, flying bombers and firing missiles... but Ukraine rarely attacks Russian territory due to psychological inferiority to a nuclear state,” Oh explained.

He dismissed critics who warned of retaliation from other countries, including sanctions, saying a South Korean nuclear programme would send a message to countries such as China, causing the North to scale back its military buildup.

“There may be some initial opposition from the international community, but I believe it will eventually gain more support,” he said.

According to a former senior US official, the Yoon administration's increased rhetoric appears to be motivated by a desire to put pressure on the US to give South Korea more say in nuclear planning.

Yoon has stated that the United States extended deterrence is “falling short of convincing” South Koreans, and Washington has agreed to increase information-sharing and tabletop drills to facilitate greater allied cooperation.

Lee Sang-Hyun of South Korea's Sejong Institute, stated this month in a report that Yoon is not seriously considering a nuclear programme and that a return of American weapons is also unlikely.

“However, in recent months, the Yoon government's nuclear non-proliferation stance has shown small but significant signs of change, if North Korea's nuclear threat becomes more visible, and South Korea follows suit, it will signal the start of an Asian nuclear domino effect,” he wrote.