In Kret Krot, a pepper-growing village home to the Bahnar ethnic group, police rounded up 62 Ha Mon adherents last year. The sect worships the Virgin Mary, and its members do not attend regular church services, according to Pham Van Dung, an official at a large church near the village.
One villager said he was unaware any link between those arrested and illegal activities.
"Maybe mistakes were made," said the 17-year-old, who gave a single name, Thuyen. "They were good people."
Regardless, four police officers who live nearby and patrol daily discourage people from joining the sect, he said.
"The police come and ask villagers not to follow the Ha Mon religion. They don't allow people to pray with the Ha Mon's Bible," Thuyen said.
Dung said that since the raid, many Ha Mon followers have fled to the jungle, where they spend much of their time in prayer.
In May, state media reported that eight of the 62 arrested were sentenced to between three and 11 years in jail for "undermining the policy of national unity." It's unclear how the other 54 arrests were resolved.
The sect members were accused of trying to get villagers to come to Ha Mon prayers so they could recruit them to the cause of independence with help from FULRO, the French acronym for the hill-tribe army that fought alongside U.S. Special Forces during the war.
"We are not arresting Protestant followers, but the followers of a church not recognized by the government," said Nguyen Thanh Cam, director of the government's Committee for Religious Affairs in Gia Lai. "These people are abusing religion to violate the law."
Many Montagnards fought with FULRO, a history that even now generates suspicion among many Vietnamese and support in the U.S. At least 12,000 Montagnards have received asylum in the United States, and some of them still call for an independent homeland for their kin.
Rong Ray, a former FULRO deputy commander who fought in the jungles of Vietnam for 12 years but now lives in the United States, said the Vietnamese state repeatedly brought up the name of his now-defunct group to imply there was a threat of violence to "discredit the Montagnard movement."
"The Vietnamese hate us because we fought and died alongside the Americans and because we are Christians," he said by telephone from North Carolina, home to the United States' largest Montagnard community.
On the government tour, authorities took the American delegation to a large new church that its pastor, Huynh Duy Linh, said had been funded in part with money from overseas Vietnamese Christians. Linh said there were seven other churches under construction, and he recounted a story about two Communist Party officials who had become Christians.
"It's only by the grace of God that we can do that," said Linh. "The need here is very big, and we can't meet the demands of our followers."
Chris Seiple, the head of the visiting Christian delegation, said Vietnam has made progress over the last 10 years, though work still needs to be done.
"In Vietnam, we have moved from persecution to isolated cases of harassment. I think Vietnam has made a choice it wants to get better at freedom of religion," said Seiple, president of the Institute for Global Engagement, a Washington-based group that promotes religious freedom. "There will be situations that will be bad sometimes, but in general we are moving forward."
But arrests continue, and so do cases of police harassment like the Hong's brief and informal house arrest. Her husband was sentenced to 11 years in jail last year for peacefully preaching against the state.
"This is not the only time and will not be the last time," Hong said. "They always try to find some way to create difficulties for our family."
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