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

"At the meeting, an in-depth discussion was made on the practical matters for holding the DPRK-U.S. summit and its procedure and ways," the news agency quoted Kim as saying.

Kim also granted amnesty to the three U.S. citizens in North Korea's custody, KCNA said.

In 2015, North Korea arrested Kim Dong Chul, a Korean-American man, on suspicion of espionage.

Last year, it detained two other U.S. citizens -- Kim Hak Song, who had worked at Pyongyang University of Science and Technology, and Kim Sang Dok, who was invited to the same university to teach accounting. They have been accused of "hostile acts" against North Korea.

In April 2016, North Korea's top court sentenced Kim Dong Chul to 10 years of hard labor for carrying out what it described as spy activities, but the details of "hostile acts" by Kim Hak Song and Kim Sang Dok remain unclear.

It was the first time North Korea has released detained U.S. citizens since June of last year, when it freed Otto Warmbier, a University of Virginia student. Warmbier, who was in a coma when he was released, died soon after returning to the United States following more than 17 months' imprisonment.

(KCNA/UPI/Kyodo)

North Korea appears to believe that the release of the U.S. citizens will help move forward the expected tough negotiations with Trump, who has pressed Pyongyang to abandon all its nuclear weapons, foreign affairs experts said.

At their summit, Kim is likely to ask Trump to ensure the continuation of North Korea's hereditary regime in return for pledging to achieve denuclearization on the divided peninsula in a "phased" and "synchronized" manner.

As for his meeting with Pompeo, Kim appreciated that it "produced satisfactory results," KCNA said, adding that the leader promised to meet with the U.S. secretary of state again.

Pompeo, meanwhile, was committed to working to make the planned Trump-Kim summit successful, according to the news agency.

Speaking at a Cabinet meeting on Wednesday, Trump said the date and location of the summit will be announced in three days.

The talks between Kim and Pompeo took place around two weeks after an inter-Korean summit on April 27, when South and North Korean leaders agreed to pursue "complete denuclearization" on the Korean Peninsula and strive to formally end the 1950-1953 Korean War.