US Secretary of State Mike Pompeo is expected to return from North Korea with three American detainees, as well as details of an upcoming summit between leader Kim Jong Un and US President Donald Trump, a South Korean official says.
Pompeo arrived in Pyongyang, the North Korean capital, on Wednesday from Japan and headed to the city's Koryo Hotel for meetings, a US media pool report said.
Trump earlier broke the news of Pompeo's second visit to North Korea in less than six weeks and said the two countries had agreed on a date and location for the summit, though he stopped short of providing details.
An official at South Korea's presidential Blue House said Pompeo was expected to finalise the date of the summit, and secure the release of three American detainees.
While Trump said it would be a "great thing" if the American detainees were freed, Pompeo, speaking to reporters en route to Pyongyang, said he had not received such a commitment but hoped North Korea would "do the right thing."
"We'll talk about it again today," he said. "I think it'd be a great gesture if they would choose to do so."
The three still being held are Korean-American missionary Kim Dong-chul; Kim Sang-duk, also known as Tony Kim, who spent a month teaching at the foreign-funded Pyongyang University of Science and Technology (PUST) before he was arrested in 2017; and Kim Hak-song, who also taught at PUST.
Until now, the only American released by North Korea during Trump's presidency has been Otto Warmbier, a 22-year-old university student who returned to the US in a coma last summer after 17 months of captivity and died days later.
Warmbier's death escalated US-North Korea tensions, already running high at the time over Pyongyang's stepped-up missile tests.