Trump says DPRK has released three US detainees

US Secretary of State Mike Pompeo arrived in Pyongyang on Wednesday, landing at the center of a whirlwind of diplomacy ahead of a planned summit between US President Donald Trump and Kim Jongun, top leader of the Democratic People's Republic of Korea.

In a sign of further progress between the sides, Trump said that the DPRK had released three US detainees, who would be returning with Pompeo.

"I am pleased to inform you that Secretary of State Mike Pompeo is in the air and on his way back from North Korea (the DPRK) with the 3 wonderful gentlemen that everyone is looking so forward to meeting. They seem to be in good health," Trump wrote in a post on Twitter.

Trump added that Pompeo and Kim had a "good meeting".

Pompeo was dispatched on the visit - his second in weeks, but first as US top diplomat - to secure a framework for the leaders' meeting, the US Department of State said in a news release on Tuesday.

"Today we're hoping to nail some of those down to say - to put in place a framework for a successful summit" between Trump and Kim, he was quoted as saying to the media on a plane flying to the DPRK.

Kim was quoted as saying on Monday by Xinhua: "I hope to build mutual trust with the US through dialogue."

He added that a political resolution of tensions on the Korean Peninsula and denuclearization should proceed in stages, with all sides moving in concert.

Pompeo's trip had not been publicly disclosed when he flew out of Washington under cover of darkness on Monday aboard an Air Force 757. Trump announced the mission on Tuesday afternoon. As for the specific date and location of the Trump-Kim meeting, Pompeo remained ambiguous, although Trump said last week that the date and location had been set.

When the flight arrived on Wednesday in Pyongyang, DPRK officials were on hand to greet Pompeo.

The rapid detente on the Korean Peninsula triggered by the Winter Olympics is a marked contrast from last year, when Trump and Kim traded insults and threats of war over Pyongyang's nuclear and ballistic missile programs. "Plans are being made, relationships are building, hopefully a deal will happen and with the help of China, South Korea (the Republic of Korea) and Japan, a future of great prosperity and security can be achieved for everyone," Trump said as he announced Pompeo's visit.

At a historic meeting inside the Demilitarized Zone on April 27, Kim and ROK President Moon Jae-in reaffirmed their commitment to a "common goal" of "complete denuclearization" of the peninsula.

Trump has said that withdrawing US forces from the ROK is "not on the table". There are 28,500 US forces based in the nation, a military presence which came as a result of the Korean War ending in 1953 with an armistice rather than a peace treaty.

AFP, Xinhua and AP contributed to this story.