WASHINGTON (AFP) - The US military confirmed that North Korea had test-fired a submarine-launched ballistic missile, condemning the hermit state's latest "provocation" and vowing to raise concerns at the United Nations.

US Strategic Command said the launch of what was believed to be a KN-11 missile off the coast of Sinpo, North Korea, "did not pose a threat to North America", citing analysis by the North American Aerospace Defense Command.

The missile, launched at 2029 GMT on Tuesday (4.29am Wednesday, Aug 24, Singapore time), fell into the Sea of Japan some 480km off the coast of North Korea.

"Our commitment to the defence of our allies, including the Republic of Korea and Japan, in the face of these threats, is ironclad," said Commander Gary Ross, a Pentagon spokesman.

"We remain prepared to defend ourselves and our allies from any attack or provocation.

"We call on North Korea to refrain from actions that further raise tensions in the region and focus instead on taking concrete steps toward fulfilling its commitments and international obligations."

Several UN Security Council resolutions demand that Pyongyang suspend all of its ballistic missile programme activities.

"We intend to raise our concerns at the UN to bolster international resolve in holding the DPRK accountable for these actions," Commander Ross said, using an acronym for the North's formal name.

The State Department issued a similar statement.