U.S. National Security Advisor Jake Sullivan speaks to the media about the war in Ukraine and other topics at the White House in Washington, U.S., March 22. Reuters-Yonhap

North Korea is currently in a provocation cycle that may last for weeks or even months, U.S. National Security Advisor Jake Sullivan said Thursday.

Sullivan also said the North will continue efforts to advance its nuclear weapons and missile programs, but that the capability to hit the U.S. mainland has yet to be proven.

"A few weeks ago, they tested an intercontinental ballistic missile, which they had not done previously, they had not done since 2017. So yes, they are in a pattern of provocation, pattern of testing," Sullivan said in a seminar hosted by the Economic Club of Washington D.C., a non-profit organization based in Washington.

"I think you will hear more out of North Korea in terms of its efforts to advance its nuclear program and its missile program in the weeks and months ahead," he added.

The remarks come as North Korea celebrates the anniversary of the birth of late founding leader Kim Il-sung, Friday (KST), an occasion that has often been marked by a show of military strength.