Pompeo made the statement during a Senate Foreign Relations Committee hearing on Donald Trump’s meeting with Russian President Vladimir Putin in Finland and his June 12 summit in Singapore with North Korean leader Kim Jong-un. Kim had committed to the “complete denuclearisation” of the Korean Peninsula during the summit.

Pompeo declined to respond when asked whether North Korea was continuing to pursue submarine-launched ballistic missiles or whether its nuclear programme was advancing generally.

Pompeo said the US 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.”

After the historic summit with Kim, Trump tweeted that “there is no longer a nuclear threat from North Korea,” but he has faced criticism about the lack of progress towards denuclearisation. Pompeo insisted that “progress is happening” and that Trump is “upbeat about the prospects of North Korean denuclearisation”, AFP reported.