US President Donald Trump sees 'progress' on North Korea talks

US President Donald Trump says he sees "possible progress" in denuclearisation efforts with North Korea after South Korea said Pyongyang would be willing to meet with the US and suspend nuclear tests while talks proceed.

The US, South Korea and China responded with cautious optimism about North Korea's willingness to talk, a development that follows months of insults and threats of war between Trump and the North.

But some US and South Korean officials said a breakthrough remained unlikely after the failure of previous talks, adding that North Korea may be trying to buy time to develop its weapons programs and seek relief from punishing American and UN sanctions.

"Possible progress being made in talks with North Korea," Trump wrote in a Twitter post on Tuesday.

"For the first time in many years, a serious effort is being made by all parties concerned. The World is watching and waiting! May be false hope, but the US is ready to go hard in either direction!"

There was no immediate comment from Pyongyang.

The news came as a South Korean delegation returned from a first meeting with North Korean leader Kim Jong Un in Pyongyang on Monday.

The two sides will hold their first summit in more than a decade next month at the border village of Panmunjom, said Chung Eui-yong, the head of the South Korean delegation. The last inter-Korean summit was in 2007 when late former president Roh Moo-hyun was in office.

"North Korea made clear its willingness to denuclearise the Korean peninsula and the fact there is no reason for it to have a nuclear program if military threats against the North are resolved and its regime is secure," Chung told a media briefing.

Chung cited North Korea as saying it would not carry out nuclear or missile tests while talks with the international community were under way. North Korea has not carried out any such tests since last November. North Korea also is willing to discuss normalising ties with the United States, Chung said.

China encouraged North and South Korea to continue their reconciliation efforts.

US Vice President Mike Pence, who visited South Korea during the Olympics, said Washington will continue to apply "maximum pressure" on the North.

In Washington, US intelligence officials said it was too early to assess North Korea's willingness to consider denuclearisation.

"Hope springs eternal but we need to learn a lot more relative to these talks. 

And we will," US Director of National Intelligence Dan Coats told a Senate Armed Services hearing.

The director of the US Defense Intelligence Agency, Lieutenant General Robert Ashley, told the same hearing that he did not share a sense of optimism, adding, 

"That's kind of a 'show me,' and so we'll see how this plays out."

Three US officials who follow events on the Korean peninsula cautioned against getting too optimistic, saying there was no indication the North has abandoned its nuclear ambitions.