"Our intelligence does reflect the genuine possibility" of nuclear-capable missile tests or a nuclear weapon test around the time of Biden's trip, National Security Advisor Jake Sullivan said.

Biden departs Thursday for a series of summits hosted by US allies South Korea and Japan.

Sullivan said it was possible that North Korea, which has defied UN sanctions in conducting an array of missile tests this year, could use Biden's visit to stage "provocations."

This could mean "further missile tests, long range missile tests or a nuclear test, or frankly both, in the days leading into, on or after the president's trip to the region," he said.

The Biden administration is prepared to "make both short and longer term adjustments to our military posture as necessary to ensure that we are providing both defensive deterrence to our allies in the region and that we're responding."

Sullivan said a potential response was being "closely" coordinated with South Korea and Japan and that he had also spoken about the issue with his Chinese counterpart earlier Wednesday.