SEOUL, South Korea — The soldier spoke in a shaky voice, describing how he had lived like a beggar in South Korea and smoked “cigarette butts thrown by American G.I.s.” As he told listeners over the radio, he had fled his South Korean unit in Vietnam, defecting to the “bosoms” of North Korea.
South Korea labeled the 23-year-old soldier, Ahn Hak-soo, as a defector, and his family members as potential enemies of the state. His brother, Ahn Yong-soo, said that when he was a teenager, he was tortured by military intelligence agents who used electricity or water laced with salt and pepper. Later, he said they forced him to quit his job as a schoolteacher.
South Korea, which once victimized innocent citizens in the name of guarding against the Communist North, is still struggling to come to terms with its past.
Nearly 320,000 South Korean troops served in Vietnam, the largest foreign contingent fighting alongside the Americans. But when they withdrew in 1973, their top commander, Lt. Gen. Lee Se-ho, claimed that no South Korean soldier was held prisoner. Mr. Lee’s command insisted that several missing soldiers, including Hak-soo, were not prisoners of war, but either deserters or defectors not worth repatriating, according to declassified documents.
Mr. Ahn helped shatter that official narrative.
In 2009, South Korea finally recognized Hak-soo as a prisoner of war, the first Vietnam War veteran so designated by the country. The government now believes he was captured by Vietcong guerrillas and abducted to North Korea, which used him for propaganda.
“In South Korea, few have been interested in Vietnam War P.O.W.’s,” said Mr. Ahn, 67, a Christian pastor. “People considered being held prisoner by the enemy shameful and dishonorable.”
Mr. Ahn continues to fight for a formal investigation and an apology.
After more than 20 lawsuits, South Korean courts recognized Mr. Ahn as a victim of torture and paid him $73,000 in damages but refused to reinstate him as a schoolteacher. Another court denied awarding compensation for his family’s sufferings, accepting the government’s argument that there was no evidence of wrongdoing and the statute of limitations had long expired. North Korea has not admitted to kidnapping his brother or confirmed his fate.
“The South Korean government clearly neglected its duty to protect its own citizens,” said Heo Man-ho, a political scientist at Kyungpook National University.
“At least Ahn Hak-soo had a brother who has fought tenaciously to clear his name,” he added, “but no one has stepped forward for other Vietnam War soldiers who were recorded as killed in action but likely ended up in North Korea.”
Mr. Ahn’s fight is part of the country’s broader reflection over past human rights violations that officials justified by pointing to the Communist threat from the North. In May, South Korea’s Parliament passed a bill to relaunch the Truth and Reconciliation Commission; the commission’s investigations into such violations had been halted in 2010 under a conservative government.
Mr. Ahn plans to take his family’s case to the commission.
“When my brother turned up in North Korea, it was enough for the authorities to label him a defector,” he said. “And our entire family was shattered.”
Hak-soo, the second child in the family of five sons in Pohang, South Korea, was dispatched to Vietnam in 1964 as a radio man with the First Korean Mobile Army Surgical Hospital near Saigon, now Ho Chi Minh City. In his last letter home, he said he would return on Sept. 16, 1966. He went missing a week before on a trip to pick up medical supplies.
During the Cold War, South Korea blacklisted families whose relatives ended up in North Korea, making sure that they did not advance in its staunchly anti-Communist society. Counterespionage agents surveilled them, often extracting false confessions through torture that they were in contact with their relatives in the North.
After Hak-soo showed up in North Korea, Mr. Ahn’s father was forced to quit as a primary school principal. Mr. Ahn, then a teenager, was called “commie’s little brother” by his high school teachers.
The Defense Security Command, the counterespionage arm of the military, had its undercover local office adjacent to his school. When Mr. Ahn was outside, he said, armed officials there would peek over the wall and hail him over for interrogation.
“An agent put a pistol on my head and pulled the trigger,” Mr. Ahn wrote in “Whitewash and Truth,” a memoir he published in 2014. “It had a tremendous impact — as if my brain exploded in a terrible sound of death.”
When Mr. Ahn became a primary schoolteacher in 1975, the agents appeared at his school in Seoul, interrogating and beating him in the janitor’s office. He was forced to resign five years later and sign a document telling him to keep quiet about what happened — or he would be punished for “an act that benefits the enemy.”
Mr. Ahn has moved his family 31 times, but he said the agents followed him like “leeches.” In 1984, he flew to Britain to study divinity at the University of Aberdeen and later at Cambridge. Government agents showed up there, too — an incident so traumatic that Mr. Ahn had to curtail his studies and return home for medical treatment, a South Korean pastor who befriended him in London said in a signed statement submitted to courts.
The Defense Security Command put Mr. Ahn’s family under surveillance until at least 1993, according to files from the organization, which was reorganized and renamed in 2018 as part of a reform of the once-infamous military spy agency.
Mr. Ahn was thinking of emigrating abroad for good in 2008 when a reporter sent him a 380-page file of recently declassified Foreign Ministry documents that mentioned his brother’s name. Hopeful that he could force some change, he filed several freedom of information requests with military and intelligence agencies.
In the documents, he found that his brother’s unit in Vietnam had hushed the disappearance for weeks.
One army document said that Hak-soo “went over” to North Korea “disgruntled.” One said he had run up “a large debt because of his complicated relationships with women,” so he “defected” and then was “kidnapped” to North Korea.
Another document said it was clear that he was “kidnapped” to the North, but still called him a “defector.” Some documents misstated Hak-soo’s home address, age and military serial number, as well as the year he went missing.
He also learned from the files that a North Korean spy, who defected to South Korea in 1976, told his interrogators that Hak-soo was executed in 1975 after a failed attempt to flee the North through the border with China. In the military file, the former spy, Kim Yong-kyu, was quoted as saying that Hak-soo “regretted defecting to the freedom-less North.”
Mr. Kim testified before a government panel in 2009, saying that North Korea lied when it said the soldier defected to the North. The panel ultimately ruled that Hak-soo was abducted, a ruling that forced the military to recognize him as its first P.O.W. in Vietnam.
Such cases, said Han Sung-hoon, a sociologist at Yonsei University in Seoul, show how anti-Communist agencies have defended their actions by “regenerating an antagonistic relationship with North Korea, even fabricating spy cases if needed.”
Mr. Han, who had served in the Truth and Reconciliation Commission, said the investigations of human rights violations have often been stymied by the reluctance of perpetrators to come clean for fear that they would be “branded betrayers and ostracized.”
Mr. Ahn is undeterred. He has continued to collect documents and statements from anyone who had information about his brother, which he plans to present before the newly revived commission.
“Both Koreas used and then abandoned my brother,” Mr. Ahn said.