Mr. Moon served as diplomatic middleman between the U.S. and North Korea following the North's increasingly powerful string of weapons tests and Trump's threats of military action in 2017.

President Donald Trump says his planned summit with North Korean leader Kim Jong Un will take place in Hanoi.

North Korea, meanwhile, has called on the United States to ease global economic sanctions and allow it to receive humanitarian aid from other countries, saying it has already begun to take concrete steps toward denuclearization.

Biegun said in his speech that the United States had told North Korea it was prepared to pursue commitments made in Singapore "simultaneously and in parallel", and that Washington is willing to discuss "many actions" to improve ties and entice Pyongyang to give up its nuclear weapons.

Intercontinental ballistic missiles are driven past the stand with North Korean leader Kim Jong Un and other high-ranking officials during a military parade marking the 105th birth anniversary of country's founding father Kim Il Sung, in Pyongyang April 15, 2017.

A year of mostly fruitless diplomacy has led to serious doubts about Mr. Kim's sincerity and Trump's ability to force North Korea to significantly reduce the threat its nuclear weapons pose to the region and world.

The president tweeted the location on Friday, saying his representatives had just left North Korea after a "productive meeting" on the February 27-28 summit.

The Yomiuri ShimbunWill the United States and North Korea be able to bridge differences in their respective standpoints over the North's denuclearization this time around?

On Wednesday, Stephen Biegun, U.S. special representative for North Korea, arrived in Pyongyang for talks about the envisioned summit.

President Trump is looking forward to this month's summit with Kim Jong Un, saying Friday that he sees the potential of an "Economic Powerhouse" in North Korea.

DPRK is the acronym of North Korea's official name, the Democratic People's Republic of Korea.

And in return, it's likely that Washington is considering offering some type of assistance for the North's economic development.

"He may surprise some but he won't surprise me, because I have gotten to know him & fully understand how capable he is", Trump said.

But the North has argued that it should be rewarded for steps taken so far, including the demolition of its nuclear testing site and the dismantling of some missile testing facilities.

"Denuclearization will be hard because North Korea wants to keep nuclear weapons, and the United States wants them all gone", Lee Sang-won, a retiree, said Thursday at a bustling Seoul train station.