U.S. national security adviser John Bolton, known as one of the most hawkish officials in the Trump administration, has said that Washington would roll back crushing sanctions on North Korea if the U.S. sees "a significant sign" of steps toward denuclearization.

Bolton alluded to the possibility of easing the tough measures in an interview Friday with The Washington Times. The comment marks a stunning reversal for Bolton, who in February last year called for preemptively bombing North Korea.

"President Trump ... has said repeatedly that North Korea has not engaged in nuclear tests," he said when asked about progress on the issue. "North Korea has not engaged in missile tests. What we need from North Korea is a significant sign of a strategic decision to give up nuclear weapons and it is when we get that denuclearization that the President can begin to take the sanctions off."