The United States says it will not remove North Korea from a blacklist of state sponsors of terrorism until the North agrees to a way to verify its nuclear weapons program.

Monday was the soonest that the U.S. could remove North Korea from the list in exchange for its disclosure of its nuclear programs in June.

But State Department spokesman Robert Wood told reporters the U.S. will not grant the North the concession until it agrees to a "strong verification regime." He declined to provide specifics, saying the North Koreans know what they have to do.

North Korea has not been tied directly to terrorism since its agents planted a bomb on a South Korean commercial jetliner in 1987 and is eager to be removed from the U.S. blacklist.