The US has strongly condemned North Korea's latest launch of two ballistic missiles, describing it as "threatening and provocative".
"We strongly condemn these and North Korea's other recent missile tests, which violate UN Security Council Resolutions explicitly prohibiting North Korea's launches using ballistic missile technology," State Department spokesman John Kirby told reporters on Tuesday.
"The US is aware of the reports that North Korea fired two ballistic missiles. We are monitoring and continuing to assess the situation in close coordination with our regional allies and partners," he said.
UN resolutions ban North Korea from any use of ballistic missile technology, although it regularly fires short-range missiles into the sea off its east coast.
"These provocations only serve to increase the international community's resolve to counter the North Korean's prohibited activities, including through implementing existing UN Security Council sanctions," Kirby said.
The US intends to raise its concerns at the UN to bolster international resolve in holding the North Korean accountable for these provocative actions.
Stressing the need for a united response, he said the US will stand with its allies, including South Korea and Japan to defend from any attack or provocation.
"Our commitment to the defence of our allies, including the Republic of Korea and Japan, in the face of these threats, remains Ironclad. We remain prepared to defend ourselves and our allies from any attack or provocation," he said.
"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," the spokesman said.
Earlier in the day, US President Barack Obama extended national emergency against North Korea.
Describing the move as "destabilising and provocative action" Obama said, "North Korea's pursuit of nuclear and missile programs and other provocative, destabilising and repressive action and policies continue to constitute an unusual and extraordinary threat to the national security, foreign policy, and economy of the United States.