U.S. National Security Advisor Jake Sullivan said the United States is analyzing North Korea's recent submarine-launched cruise missile tests, warning that it will not accept acts undermining security.

Sullivan made the remarks to reporters on Monday on board Air Force One en route to California with President Joe Biden.

The security advisor said that the U.S. will not let any steps taken by North Korea deter or constrain U.S. actions necessary to safeguard stability on the Korean Peninsula, indicating that the North's provocation will not affect the South Korea-U.S. combined military exercises that kicked off on Monday.

Sullivan added that the U.S. is still analyzing the launch to determine what capabilities it demonstrated.

U.S. State Department spokesperson Ned Price said that Washington will work with its partners across the Atlantic to hold North Korea accountable, with additional methods under consideration to that end.

North Korea claimed on Monday that it test-fired two strategic cruise missiles from a submarine the previous day.