China is cracking down on Christian charity groups near its border with North Korea, missionaries and aid groups say, with hundreds of members of the community forced to leave the country and some who remain describing an atmosphere of fear.
The sweep along the frontier is believed to be aimed at closing off support to North Koreans who flee persecution and poverty in their homeland and illegally enter China before going on to other nations, usually ending up in South Korea.
The South says the number of such defections is showing signs of a slight slowdown this year.
Beijing has not charged anyone with any crime, but two sources with direct knowledge say a Korean-American man who ran a vocational school in the border town of Tumen was being investigated by Chinese authorities.
Earlier this month, China said it was investigating a Canadian couple who ran a coffee shop in Dandong city on suspicion of stealing state secrets.
As many as one third of the 3,000 South Korean missionaries working in China, largely near the North Korean border, have been forced out, most by having their visas refused, said Simon Suh, a Christian pastor who runs an orphanage in Yanji, a city near Tumen.
Many South Korean churches have been shut down, he said, quoting information he had received from several Christian groups in the region.
“Peter [Hahn]'s school in Tumen and Kevin Garratt's coffee shop were two organizations that were really well known,” said Suh. “Both of them being cracked down on is a huge blow to everyone, to every activist who is involved with North Korea.”
The missionaries in the remote and mountainous region are usually reserved, but during a recent visit by a Reuters reporter, they seemed especially fearful of speaking to outsiders and appeared to be worried about being followed by security forces.
South Korean and Western missionary groups run schools, orphanages and cafes in the region and channel food and other aid into North Korea. But some of them have also been caught up in helping North Koreans who have fled their isolated country.
There was no firm evidence, however, that Hahn or the Garratts were involved in the so-called underground railroad, helping people escape from North Korea and clandestinely facilitating their journey to the South, usually through a third country.
Statistics released by South Korea's Ministry of Unification show the number of North Korean refugees to defect to the South has slightly decreased to about 700 in the first six months of the year, although it would be too soon for the crackdown to take full effect.
In the last two years, about 1,500 people have successfully made the journey each year.
“They have built more fencing, re-organized the border guards, increased punishments for failed escapees and have increased cooperation with the Chinese authorities to disrupt networks helping those who manage to escape,” said Sokeel Park of LiNK, an NGO that works with North Korean defectors.
“Obviously, the screw is tightening all along the border,” said a Christian activist in South Korea, who did not want to be named due to the sensitivity of the situation. “There has been a concerted effort to break up the network of people who help North Koreans - on either side of the border.”
Another source working in the region said: “I believe that the D-Day has come or is coming soon for individuals, businesses and schools who have set up fronts to do North Korea-related humanitarian and refugee works.”
It was not immediately clear why China, North Korea's main ally and economic benefactor, was cracking down on missionaries in the region, but experts said it had cooperated with North Korea in the past along the border.
China's Foreign Ministry did not respond to a request for comment.
While China can be suspicious of Christian groups and President Xi Jinping has launched a wide crackdown on underground churches, foreign missionaries usually operate without too much harassment.
Suh said a South Korean pastor who ran another orphanage for children of North Korean defectors had been detained and interrogated for weeks before being forced to leave the country this month.
Chinese staff employed by the pastor, who Suh asked Reuters not to name due to the sensitivity of the issue, had gone into hiding after threats from authorities.
Suh added he himself had been interrogated by authorities during a recent visit to the neighboring town of Hunchun.
The crackdown on the groups, many of which had been established in the region for years, has taken place over the last six months, foreign Christian sources working near the border told Reuters.
“There has been a mass exodus of South Korean missionaries,” said the owner of a Christian group business in Yanji. “Many organizations are pulling people out because they're scared, and certain blocks of people have just disappeared.”
Hahn, 74, runs a Christian NGO that sits a few blocks from the Tumen river, which faces the North Korean border town of Namyang. Chinese authorities have been interrogating him for weeks, and he has not been allowed to leave the country, sources with direct knowledge of the matter told Reuters.
Marie Harf, a spokeswoman for the U.S. State Department in Washington, said she was aware of the reports about Hahn's questioning but could not comment further for reasons of privacy.
The issue could come up during a three-day visit to China by Robert King, the U.S. special envoy on human rights in North Korea. King's visit starts on Monday.
Hahn also co-owns a coffee shop called the Green Apple next door to the school, said Bob Grainger, his British business partner at the cafe.
Grainger said the cafe, which sells sweet buns and plays light South Korean pop songs, is functioning as normal, but that he did not know whether authorities would allow him to maintain his visa, up for renewal later this month.
“The Canadian case will tell us a lot about what to expect, we're looking to that,” Grainger said. “It's not directly related to us but it tells us about the attitude of the authorities.”
Grainger added that despite police visits, he regularly sees Hahn coming and going and that teachers and students are going about their business at the school, although there are no classes during summer.
Hahn had also visited the hospital to be treated for stress, a source with direct knowledge of the matter said.
Administrators were at work last week at the airy school, decorated with potted plants next to big windows, but Hahn was nowhere to be found.
“We're sorry, but the police will not allow the head of the school to see anybody,” a school administrator said. “Things are extremely tense at the moment.”
She said Hahn and other employees of the school could not answer further questions without seeking permission from the police.