North Korea on Sunday said military cooperation between South Korea, the United States and Japan has entered a "very dangerous stage" that could drive the Korean Peninsula into the brink of a nuclear war.

No one can ensure the military campaign between the three is not leading to "a nuclear war and the third world war," the Rodong Sinmun, the North's main newspaper, said on Sunday.

"We have established the strongest response strategy by arming ourselves with nuclear weapons to protect our sovereignty and the wellbeing of our people from the war of aggression by the US and its followers," the paper said.

The paper called its military activities "self-defensive" to "thoroughly safeguard ourselves against the enemy's warmongering" and "to protect peace and stability of the region."

"The move for tightening the US-Japan-puppet south Korea triangular military alliance ... is a potential factor which can put the situation on the Korean peninsula into an uncontrollable phase," the North's Korean Central News Agency said on Saturday.

Early last month, the three nations staged a trilateral maritime interdiction exercise in waters south of the Korean Peninsula, for the first time in seven years, to strengthen security coordination against North Korean threats. (Yonhap)