There are reports that three Americans detained in North Korea have been relocated to a Pyongyang hotel and are receiving good food and medical care.
The reports could suggest the three may be released as a gesture of good will, amid preparations for a meeting between leader Kim Jong-un and US President Donald Trump.
Mr Trump has said the US is “fighting very diligently” to win their freedom.
“As everybody is aware, the past Administration has long been asking for three hostages to be released from a North Korean Labor camp, but to no avail,” he said.
Two of the detainees were jailed in 2017, after Mr Trump became president.
The US State Department has said it can not confirm the validity of the reports on the prisoner move, which came from Choi Sung-ryong, a South Korean activists with contacts in the North.
But a spokeswoman said the US was “working to see US citizens who are detained in North Korea come home as soon as possible”.
Here’s what we know about the three men.
Kim Hak-song worked at the Pyongyang University of Science and Technology (PUST) and was held on suspicion of “hostile acts” on 6 May 2017. He was reportedly detained while in Pyongyang Station.
The university, which mostly teaches the children of North Korea’s elite, was founded in 2010 by a Korean-American Christian entrepreneur, with much of the costs funded by US and South Korea Christian charities.
Several foreign lecturers are thought to teach there.
Kim Hak-song had previously described himself as a Christian missionary who intended to start an experimental farm at PUST, Reuters news agency reported, citing an online post by Mr Kim.
He is, reports say, an ethnic Korean born just across the North Korean border in China who emigrated to the US in the 1990s. He is said to have gone on to study agriculture in Yanbian, a Chinese prefecture which borders North Korea, before moving to Pyongyang.
Kim Sang-duk/Tony Kim
Two weeks before Kim Hak-song was arrested, Kim Sang-duk – also known as Tony Kim – was detained on espionage charges.
He was trying to leave the country after spending a month working at PUST. South Korean media said he was 55 and had been involved in humanitarian work in the North.
“Some officials at PUST told me his arrest was not related to his work at PUST,” the chancellor of the university, Chan-Mo Park, told Reuters news agency.
“He had been involved with some other activities outside PUST, such as helping an orphanage.”
Mr Kim studied accounting at two American universities and had worked as an accountant in the US for more than a decade, his Facebook page says.
He had also taught in Yanbian.
A South Korea-born US citizen, Kim Dong-chul is a pastor in his early 60s.
He was detained in 2015 on spying charges and sentenced to 10 years’ hard labour in 2016.
Before his trial, he was presented at a government-arranged press conference, where he apparently confessed to stealing military secrets in collusion with South Korea – a claim rejected by Seoul.
In an interview with CNN in January 2016, Mr Kim said he lived in Fairfax, Virginia.
He said he used to run a trading and hotel services company in Rason, a special economic zone near the border zone in north-east North Korea.
He told CNN he had left a wife and two daughters behind in China, but had had no contact with them since his detention.