CIA director Mike Pompeo has offered assurances there is "nothing imminent" in the US standoff with nuclear-armed North Korea but said he would not be surprised if Pyongyang conducts another missile test.

Pompeo's remarks came on Sunday, capping a week in which US President Donald Trump vowed "fire and fury" if North Korea continued to threaten the United States with nuclear weapons, and Pyongyang countered by announcing plans to test-launch missiles towards Guam.

Asked how worried people should be, Pompeo told Fox News on Sunday: "There's nothing imminent today. But make no mistake about it. The increased chance that there will be a nuclear missile in Denver is a very serious threat."

Pressed on his "nothing imminent" statement, Pompeo said: "What I'm talking about is, I've heard folks talking about that we have been on the cusp of a nuclear war. [There is] no intelligence that would indicate we are in that place today."

He said the US intelligence community has "a pretty good idea" about what's going on in North Korea.

Pompeo also said that he believed North Korea would continue to develop its missile capabilities under its leader Kim Jong-un.

"He conducted two in July, so it wouldn't surprise me if there's another missile test," Pompeo said.

READ MORE - Why a war with North Korea is unlikely

Also on Sunday, the top US military officer, Marine Corps General Joseph Dunford, travelled to South Korea.

After meeting the South Korean leader, he is expected to meet the heads of Japan and China.

Dunford, the chairman of the Joint Chiefs of Staff, told reporters travelling with him that he aimed to "sense what the temperature is in the region".

He will also discuss military options in the event the "diplomatic and economic pressurisation campaign" fails.

"We're all looking to get out of this situation without a war," Dunford said.