South Korea should build nuclear weapons to bolster its defenses against North Korea, even at the risk of international repercussions, the mayor of its capital city said, arguing that the country cannot be bound by the goal of denuclearization.

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

"North Korea has nearly succeeded in miniaturizing and lightening tactical nuclear weapons and secured at least dozens of warheads," Oh said. "We've come to a point where it is difficult to convince people with the logic that we should refrain from developing nuclear weapons and stick to the cause of denuclearization."