U.S. Secretary of State Mike Pompeo has said that he will not put a timeline on negotiations with North Korea to rid it of its nuclear weapons, an apparent reversal of earlier remarks that the White House would seek "major disarmament" by Pyongyang by January 2021, the end of President Donald Trump's first term.

Pompeo said in an interview reported Monday that the administration would regularly assess the regime's seriousness about abandoning its nuclear program, a pledge North Korean leader Kim Jong Un made to Trump at their historic June 12 summit in Singapore.

"I am not going to put a timeline on it, whether that's two months, six months, we are committed to moving forward in an expeditious moment to see if we can achieve what both leaders set out to do," Pompeo said in the interview conducted Sunday.