"If Chairman Kim has reneged on the commitments he made to President Trump it's deeply disappointing," Pompeo said after North Korean leader Kim Jong Un declared an end to moratoriums on nuclear and intercontinental ballistic missile tests.

"We have lived up to our commitments. We continue to hold out hope that he will live up to his," the top US diplomat told CBS television.

"President Trump has taken an approach where we have tried to create a diplomatic pathway. We hope that the North Koreans will reconsider, that they will continue down that pathway.... We want peace not confrontation."

In a separate interview with Fox News shortly after state media quoted Kim as threatening a demonstration of a "new strategic weapon" soon, Pompeo urged the North Korean leader to think again.

"We're hopeful that ... Chairman Kim will make the right decision and he'll choose peace and prosperity over conflict and war.

"I saw that reporting. I hope he doesn't go in that direction."

A self-imposed ban on such tests has been a pillar of nuclear diplomacy between Pyongyang and Washington over the past two years, which has seen three meetings between Kim and US President Donald Trump, but little tangible progress.