North Korea said it carried out an "important final-stage test" for a spy satellite, after South Korea's military over the weekend detected launches of two medium-range ballistic missiles.

State Department spokesman Ned Price said the launches, the latest in a year that has seen a slew of missile tests, "violate multiple UN Security Council resolutions."

"We believe they pose a threat to the region and to the international community more broadly," Price said, adding that the US commitment to the defense of South Korea and Japan was "ironclad."

"We remain committed to doing all that we can to make that clear, even as we seek to make clear to the DPRK that we harbor no hostile intent," Price said, referring to the North by its official name, the Democratic People's Republic of Korea.

"We are committed to a diplomatic approach and we continue to call on the DPRK to meet us in our continued calls for practical, pragmatic diplomacy," he said.

North Korea has snubbed offers from President Joe Biden's administration for talks, instead describing the United States as hostile.

Last month, North Korea tested an intercontinental missile that could hit the US mainland and US and South Korean intelligence believe Pyongyang has made preparations for a seventh nuclear test.

Former president Donald Trump broke precedent by meeting with North Korean leader Kim Jong Un three times, easing tensions but reaching no lasting agreement.