North Korea is continuing to produce fissile material for nuclear bombs in spite of its pledge to denuclearise, US Secretary of State Mike Pompeo says.
Asked at a Senate foreign relations committee hearing whether this was the case, Pompeo responded to Democratic Senator Ed Markey by saying: "Yes, that's correct. Yes, they continue to produce fissile material."
Pompeo declined to respond when asked whether North Korea was continuing to pursue submarine-launched ballistic missiles or whether its nuclear program was advancing generally.
He said he would be happy to answer the latter question if necessary in a classified setting but suggested public statements on the issue would not help "a complex negotiation with a difficult adversary".
Pompeo defended what he termed progress in talks with North Korea stemming from an unprecedented June 12 summit between President Donald Trump and North Korean leader Kim Jong-un in sometimes testy exchanges with skeptical lawmakers.
He said the United States was engaged in "patient diplomacy" to persuade North Korea to give up its nuclear weapons, but would not let the process "drag out to no end."
Briefing on his July 5-7 visit to North Korea, Pompeo said he had emphasised this position in "productive" discussions with his North Korean interlocutor, Kim Yong-chol.
He said Trump remained upbeat about the prospects for North Korean denuclearsation, but Kim needed to follow through on his summit commitments.
Pompeo said US North Korea policy was guided by a principle stated by Trump on July 17 that "diplomacy and engagement are preferable to conflict and hostility".
Trump has hailed his summit with Kim as a success, but questions have been growing about North Korea's willingness to give up a nuclear weapons program that threatens the United States.
Kim committed in a summit statement to work towards denuclearisation but Pyongyang has offered no details as to how it might go about this.
