Seoul's defense chief on Monday cast doubt on Pyongyang's threats to strike the United States or South Korea with nuclear weapons, saying that such a move would result in the country being "literally wiped off the face of the Earth."

Speaking at a security forum in Singapore that was broadcast over the internet, Defense Minister Song Young-moo also voiced skepticism that North Korean leader Kim Jong Un would use nuclear weapons for coercive purposes, including to reunify the Korean Peninsula on his terms.

"Should North Korea use nuclear weapons against the United States or South Korea, North Korea would be literally wiped off the face of the Earth," Song said.