Pompeo arrived in the North Korean capital Pyongyang on Wednesday to prepare for the summit, while the US president had signaled the possibility that three Americans detained in the country could soon be released.
The three US citizens were imprisoned for more than a year. Their release is said to have removed a source of diplomatic friction between Washington and Pyongyang ahead of the summit between the two leaders.
The three men—Kim Dong-chul, Tony Kim and Kim Hak-song—flew out of Pyongyang on Pompeo’s plane and will land in Joint Base Andrews in Maryland, according to another Donald Trump tweet, Presstv reported.
Pompeo was on his second trip to Pyongyang in just over a month. He also met with Kim Yong Chol, a North Korean general who has played a key role in the North’s recent outreach to South Korea, calling him a “great partner” in preparing for the coming summit.
"I have high expectations the United States will play a very big role in establishing peace on the Korean Peninsula," Kim Yong-chol said in the meeting.
Pompeo has been asking for the release of the detainees for 17 months.
One of the detainees, Kim Dong-chul, a pastor in his 60s, was detained in 2015 for spying charges and sentenced to 10 years of labour in 2016.
The other two have been imprisoned since 2017. Tony Kim, a Korean-American lecturer, was detained on espionage charges in April 2017. A month later, Kim Hak-song, a Christian missionary, was held on suspicion of “hostile acts.”