A former U.S. envoy said Thursday that he expects the three American detainees in North Korea to be released during an upcoming summit between the two countries' leaders.

Bill Richardson, former governor of New Mexico and former U.S. ambassador to the United Nations, said their release is one of the realistic expectations one can have of U.S. President Donald Trump's meeting with North Korean leader Kim Jong-un in May or June.

"I think that would be a deliverable that would happen at the summit," he told a forum here, before listing other humanitarian issues, such as the return of the remains of U.S. soldiers killed in the 1950-53 Korean War.

Trump said Wednesday that his administration is negotiating for the detainees' release and thinks "there's a good chance of doing it." The Americans -- Kim Hak-song, Tony Kim and Kim Dong-chul -- have been accused of espionage or "hostile acts."

Richardson, who played important roles in past dealings with Pyongyang, also said he thinks the Trump-Kim meeting could take place in Geneva or Russia.

Days shaking the world 2018-04-20 16:42
"One, I'm betting on Geneva. Second bet is one of the Russian islands," he said.

On Trump's new national security adviser, John Bolton, the former governor noted his personal ties to him as a fellow former ambassador to the U.N.

"Everybody is worried that John Bolton is going to bomb (North Korea). Relax," Richardson said. "His first job is that this summit is a success as a staff member."

Bolton recently argued for a preventive strike on North Korea, although he also said it is not his favored option. (Yonhap)