North Korea has 'brilliant potential', says President Trump

North Korea has "brilliant potential" and will be a "great economic and financial Nation one day", Donald Trump says.

The president made the comments in a tweet on Sunday as US officials arrived in North Korea and met their counterparts at the border village of Panmunjom.

"Our United States team has arrived in North Korea to make arrangements for the Summit between Kim Jong Un and myself," he said.

"I truly believe North Korea has brilliant potential and will be a great economic and financial Nation one day. Kim Jong Un agrees with me on this. It will happen!"

State department spokeswoman Heather Nauert said a "US delegation is in ongoing talks with North Korean officials" inside the demilitarised zone between North and South Korea that was created at the end of the Korean War.

Trump withdrew from the planned summit last week, but quickly announced it could get back on track.

He said on Saturday the US was still considering the 12 June date for the summit in Singapore.

"We're doing very well in terms of the summit with North Korea," Trump said at the White House.

"It's moving along very nicely. So we're looking at June 12th in Singapore. That hasn't changed. So, we'll see what happens."

Kim believes a summit with Trump will be a landmark opportunity to end decades of confrontation, South Korea's President Moon Jae-in said following his surprise meeting with the North Korean leader.

"He (Kim) also expressed his intention to put an end to the history of war and confrontation through the success of the North-US summit and to co-operate for peace and prosperity," Moon told reporters.

A statement from North Korea's state news agency KCNA said Kim expressed "his fixed will" on the possibility of meeting Trump as previously planned.