"Sustainable peace on the Korean peninsula does not happen automatically," Yoon told a joint news conference with President Joe Biden.

"We can achieve peace through the superiority of overwhelming forces and not a false peace based on the goodwill of the other side," he said.

Yoon was speaking after the Biden administration agreed to send a nuclear submarine to South Korea following months of missile tests by North Korea.

"Our two countries have agreed to immediate bilateral presidential consultations in the event of a North Korean nuclear attack and promise to respond swiftly, overwhelmingly and decisively using the full force of the alliance including US nuclear weapons," Yoon said.