Offsprings of families formed during and torn apart by war long for reunion, but even blood ties can wear thin.
Tran Van Ty had worked in the same company as his missing-inaction father for nearly two years before they met as son and father after 30 years.
"I froze outright," Ty recalls. "Suddenly anger flooded my feelings of love and longing."
The unexpected reunion took place in November 2001, entirely due to Ty's perseverance against all odds.
The father, Kim Young Ki, had named the place where his South Korean unit had been stationed in Vietnam, his Vietnamese wife, their first daughter "and almost all the information matched," says Lee Hei Young, the company director who became the bridge between son and father.
Lee asked Ty to say "father", but Ty wouldn't, the director told Thanh Nien. "I don't know why I repressed my emotion at that time. I asked him why he did not try to find us for such a long time," Ty says. "I told him to go see my mother and only when my mother accepts him as her husband, would I accept him, and he said yes.
"Still, it remains a only promise until now, and I've never got a chance to call him father."
(From left) Ngo Pang Thu Diem, Ngo Pang Thu Trang, Pang Yong SoK the father and Ngo Pang Thu Thai. The sisters are among a few lucky instances where the father has supported his children to build a better life.
Lee told Thanh Nien that Kim had been really concerned for his family in Vietnam but he could never contact them.
Kim is affected by chemicals used during the war and too weak now to fly back to Vietnam, he said.
Tran Thi Ngai from the south-central Phu Yen Province says she and Kim, then a corporal, married and had their first daughter in 1968.
Kim left and returned one time in 1970 and they had two more children, Tran Thi Kim Huong and Tran Van Tien, who was renamed Tran Van Ty later.
The war ended soon after and Kim went home. "As I didn't want to involve in any after-war issues, I burnt all the papers relating to Kim and the three children's father's name in the birth certificates was anonymous."
Ty grew up with a complex that he was "a half-blood boy with South Korean eyes" as his friends often teased him.
In 1991 he tried to enter South Korea but failed, having few documents to prove that he was half-Korean by blood. Despondent, he wandered back to Ho Chi Minh City.
Years later, many Korean social organizations were allowed to open charity vocational classes in the city for Vietnamese children of Korean descent, Ty recalled.
Ty learnt to speak Korean and every time he met a South Korean, he asked for the information about corporal Kim Chong Kil, as his mother misspelled the name, and drew blanks.
In 1993, Ty was adopted by the South Korean general director of PICO Corporation, who sent him to university in Vietnam and then to manage a textile factory in India in 1997.
Ty asked to quit three years later and continued looking for his father in Seoul.
Korea's Social Welfare Association helped Ty to get a job in the L&S Company, where his father was working.
Director Lee said Ty had told him many times about his father but "he used the wrong name and I couldn't help.
"Later when I accidentally told Kim the story, he realized that the boy was looking for him," Lee said.
After solving his own case, Ty has gone on to help more than 40 children like him meet up with their Korean fathers.
Ngo Pang Thu Trang, 37, from the south-central Khanh Hoa Province says her mother had married Pang Yong Sok in 1970 when he was working for an American shipbuilding yard at the province's Cam Ranh Harbor.
After living in Vietnam for a while, Pang revealed that he already had a family at home and in 1975 when the couple had their third child, Ngo Pang Thu Thai, the father left.
"We sent our parents' pictures to any South Korean we met, hoping that they knew something," Thai says.
The sisters met Ty in 2004, when they had almost given up.
In 2007, Ty called them to Ho Chi Minh City urgently to contact their father but when they arrived, they were informed that Pang had just left his home in South Korea, and no one knew where he was. Two sisters returned to Khanh Hoa, Thai stayed on.
The very next day, Thai was called to talk on the phone with Pang, who was in Australia. "I couldn't talk, but cried for an hour," Thai told Thanh Nien.
In April that year Pang came to Vietnam with his South Korean wife and two children.
Pang and his wife have returned later, and have helped the three sisters better their lives.
However, not every story has a happy ending.
Phan Trong Duc, also of Khanh Hoa Province, has met his father for a only few hours in the last 35 years.
His mother, Phan Thi Sen, says South Korean soldier Kim Son Kieu intended to bring her and Duc with him when the war ended, but "I didn't want to break his family there."
Based on Kim's identification disc, Ty found his place in Korea. Supported by a South Korean television program for mixed children, Kim and his wife landed in Vietnam last year.
"I had little emotion when I met him," Duc says. "I'm already accustomed to living without a father for years.
"I just think of my children. They keep asking about their grandfather." Duc says Kim promised to come another time early this year but he didn't.
"I have traveled to many places in the country, meeting South Koreans who were in Vietnam earlier. Few of them care for their half-blood children, and most forget about the past," Ty wrote in the introduction to his short story collection Nhung manh doi luan lac (Lost lives).
Ty also wrote in his poems about Americans and the French taking their children with them, while the South Koreans abandoned them. "Most of them are children of soldiers during the war."
Every time he guides a tour with South Korean veterans around the places where they used to be stationed, Ty will mention the matter of mixed children and ask the veterans to fulfill their responsibilities.
"We are humans, not scraps of the war," Ty wrote in his collection. Pham Thi Minh Tuyet of Khanh Hoa's Cam Ranh Town says she married soldier Lee Sung Hei in 1969 but has not received any information from him since he left in 1970.
"I'm very weak right now and just want him to show up one last time so that my daughter knows her father," she says.
Between 1964 and 1973, hundreds of thousands of South Korean soldiers took part in the Vietnam War, according to Ty, and more than 1,000 mixed children were born without knowing their fathers' faces.
Ty has received 500 cases in which Vietnamese women and their half-Korean children want to find their husbands and fathers.
"My wife often grumbles what I can do by myself," Ty says. "Sometimes I think she's right."
Reported by Hoang Tuan