North Korea on Wednesday freed three American prisoners who were accused of espionage, United States President Donald Trump said. The prisoners were released following US Secretary of State Mike Pompeo’s unannounced visit to North Korean capital Pyongyang earlier in the day.

“I am pleased to inform you that Secretary of State Mike Pompeo is in the air and on his way back from North Korea with the three wonderful gentlemen that everyone is looking so forward to meeting,” Trump tweeted. “They seem to be in good health.”

The president said he would meet Kim Dong-chul, Tony Kim and Kim Hak-song when they land at the Andrews Air Force Base in Maryland.

Pompeo visited Pyongyang to discuss the details for the proposed meeting between Kim Jong Un and Trump. The US president in his tweet said that the date and location for the meeting were finalised on Wednesday.

Pompeo, who earlier headed the Central Investigating Agency, met Kim Yong-chol, the vice chairman of the central committee of North Korea’s ruling party. “For decades, we have been adversaries,” the diplomat said, according to Sky News. “Now we are hopeful that we can work together to resolve this conflict, take away threats to the world and make your country have all the opportunities your people so richly deserve.”

Tensions between the US and North Korea escalated in 2017 after Pyongyang stepped up its efforts to boost its nuclear weapons programme. Trump had warned Kim Jong-un a number of times against it, and the two leaders had frequently traded ridicule, insults and threats. On April 27, at a historic peace summit between the two Koreas in Panmunjom village, the North had announced its intention to denuclearise the Korean peninsula. The two sides also vowed to end the Korean War.