North Korea defended its possession of nuclear weapons Sunday, saying it is "a means to protect peace and security in the region, not an object of contention."

Earlier this week, Pyongyang claimed it has developed nuclear warheads small enough to fit on a missile, further escalating tensions with Seoul.

"The North's nuclear weapons can never be an object of accusations as it is a means to protect the dignity and sovereignty of the nation," an unnamed spokesman for the Committee for the Peaceful Reunification of Korea was quoted as saying by the North's state media.

"South Korea should at least recognize that the treasured nuclear sword of North Korea can never be dismantled."

The statement came after U.S. Secretary of State John Kerry hinted at the possible deployment of the Terminal High Altitude Area Defense (THAAD) system, which can shoot down ballistic missiles at a higher altitude, in South Korea.

"The nuclear deterrence of the DPRK has not posed any threat to anybody but has performed the most just and responsible mission to check the U.S. wild ambition for hegemony on the forefront and preserve regional peace and stability," the spokesman was also quoted as saying by the Korean Central News Agency.

DPRK is the acronym for North Korea's official name, the Democratic People's Republic of Korea.

The spokesman warned South Korea to "stop acting recklessly" and vowed "catastrophic consequences" should it continue to take issue with the North's nuclear weapons. 

The two Koreas are technically at war since the 1950-53 Korean War ended in an armistice, not a peace treaty. (Yonhap)