The US will not be making any concessions to North Korea during forthcoming nuclear talks, according to the CIA's director.

Mike Pompeo said it was a good time to begin such discussions, claiming the secretive state led by Kim Jong Un was buckling under the pressure of US-led international sanctions.

"Never before have we had the North Koreans in a position where their economy was at such risk, where their leadership was under such pressure," he told Fox News Sunday.

"Make no mistake: while these negotiations are going on, there will be no concessions made," he added.

Amid claims the President is entering the potentially risky talks without properly considering the potential consequences, Mr Pompeo said Donald Trump understood the dangers.

"The president isn't doing this for theatre; he is going there to solve a problem," he said.

While Mr Pompeo added that "channels are open", he did not provide any details on how the US intended to proceed.

This combination of two file photos show US President Donald Trump (left) and North Korean leader Kim Jong Un | Image: Evan Vucci Wong Maye-E/AP/Press Association Images

Mr Trump, who has spent months trading insults with the leader he called "Little Rocket Man", said the US had "shown great strength" when tensions between the two countries were at their height.

At a campaign rally in Pennsylvania on Saturday night, he added that North Korea's leaders "want to make peace".

"I think it's time," he said.

Prior to the rally, he told reporters: "I think North Korea is going to go very well, I think we will have tremendous success. We have a lot of support.

"The promise is they wouldn't be shooting off missiles in the meantime, and they're looking to de-nuke. So that'd be great."

Mr Trump's deputy press secretary, Raj Shah, told ABC's This Week there could be a White House summit, or the President could meet Mr Kim in North Korea. He said the latter venue was not "highly likely", however.

An invitation to hold talks with North Korea was relayed to President Trump at the White House by South Korean national security adviser, Chung Eui-yong, who had previously met Kim Jong Un.

He told Mr Trump that North Korea's leader had pledged to halt missile and nuclear tests during negotiations.

Mr Kim is also apparently prepared to discuss denuclearisation.