North Korea on Tuesday accused the United States of driving the global nuclear order into "the worst crisis" through its "nuclear proliferation activities" and used the accusation to defend its own nuclear program.

The accusation came in a foreign ministry's "memorandum" carried by the Korean Central News Agency, hours after Vice Foreign Minister Kim Son-gyong told the UN General Assembly in New York that North Korea's nuclear program is an "irresistible" force needed to protect its sovereignty and security against external threats.

Washington has "irresponsibly abandoned its disarmament obligations as a nuclear-weapon state," the memorandum said.

Its rapid buildup of nuclear forces and "blatant" nuclear proliferation, it said, left Pyongyang no choice but to "play a more active role" "as a responsible nuclear-weapon state."

The document cast the US as the main culprit behind global nuclear proliferation, citing its nuclear buildup and modernization and its withdrawal from arms-control treaties.

North Korea also pointed to US nuclear-powered submarine cooperation with Seoul and Tokyo, and to AUKUS, a security partnership of the US, Britain and Australia, as evidence of a nuclear alliance taking shape in the Asia-Pacific region.

Such cooperation could eventually lead South Korea to develop its own nuclear weapons programs, it claimed.

This "grave reality," it said, will guide North Korea's actions as it moves to "safeguard the security interests of our country and the region."

North Korea's Vice Minister of Foreign Affairs Kim Son-gyong addresses the 81st session of the United Nations General Assembly at the UN headquarters on Monday, in this AP photo. (AP-Yonhap)
North Korea's Vice Minister of Foreign Affairs Kim Son-gyong addresses the 81st session of the United Nations General Assembly at the UN headquarters on Monday, in this AP photo. (AP-Yonhap)

The memorandum was seen as an effort by North Korea to defend its nuclear weapons by stressing what it called Washington's double standard on nuclear policy and proliferation, an official at South Korea's unification ministry told reporters.

According to the official, the North issued an official statement in the form of a "memorandum" for the first time since May last year, when its foreign ministry criticized the US missile defense system.

Pyongyang uses the term when addressing the historical background of a particular issue, the official explained. (Yonhap)