When Tycoria Johnson told her family she was going to Vietnam to help recover the remains of an American killed there during the war, her mother was proud -- but anxious.
Seventeen years earlier, Johnson's father died in a helicopter crash on a similar mission to find some of the 1,600 US servicemen and women killed in the Vietnam War whose bodies have still not been located.
"The last time (my mother) had a family member here, he didn't come back, so she was kind of nervous," said 26-year-old Johnson, a radio frequency transmission systems technician stationed in Japan with the US Air Force.
In an unlikely twist of fate, Johnson was assigned to help recover the remains of a Marine pilot whose plane crashed during a night mission in central Quang Ngai province in 1966.
She spent weeks scouring the forest for bone shards or tooth fragments, learning a few words of Vietnamese, the same work her father, US Army Sergeant First Class Tommy Murphy, did before he died in 2001.
He was among seven Americans and nine Vietnamese killed when their helicopter slammed into the side of a mountain in bad weather.
Johnson said her trip was a chance for closure.
"I feel like he didn't complete it, so I wanted to do that for him, to say that he finished the mission," Johnson told AFP, sitting near a framed photo of her father working on a dig site in Vietnam.
Johnson was on the mission with the US agency in charge of recovering American remains around the world, the Defense POW/MIA Accounting Agency (DPAA).
It has been working in Vietnam for more than 30 years, before the former war foes established diplomatic ties in 1995.
The agency was born out of a war-era effort by the wives of American POWs in Vietnam who demanded US leaders do more to get their imprisoned husbands home, many of whom were held in the infamous "Hanoi Hilton" prison in the capital of the Communist North.
Now it focuses on returning bodies and has repatriated more than 1,000 American remains from the Vietnam War since 1973, including fallen soldiers found in neighbouring Laos, Cambodia and China, according to DPAA figures.
Of the more than 1,600 still unaccounted for, about 1,200 are in Vietnam.
That includes the pilot whose remains Johnson was looking for, though her team never found him.
Instead she capped her mission at a stoic repatriation ceremony in Danang for three other soldiers whose remains found in Vietnam were placed in a box wrapped with an American flag to be shipped to the US state of Delaware for DNA testing.
DPAA works around the world to recover US war missing. Those unaccounted for include 72,000 from World War II and 7,700 from the Korean War.
A further 126 are listed as unaccounted for from the Cold War -- many of them aircrew who went missing during reconnaissance flights over or near former Soviet bloc countries.
Its reach is broad: the agency has brought home remains from Papua New Guinea to China, Pearl Harbor and the former Soviet Union, and has even identified remains of soldiers handed over by North Korea decades ago.
All the sites share a similar challenge, and Vietnam is no exception.
"Time is our biggest enemy," DPAA director Kelly McKeague told AFP in Hanoi. "Because witnesses are ageing and dying it's important for us to accelerate the pace and scope."
Many bodies are in remote jungle terrain or on land that is due to be paved over for shopping malls or apartment complexes in the fast-developing country.
Plus, the acidic soil that eats away at bone erodes evidence for search teams to recover.
McKeague said it's impossible to estimate how long it will take to bring back the remaining soldiers from the region, with only the "hard cases" remaining. Hundreds more are deemed non-recoverable.
The number of unaccounted-for Americans pales compared to the estimated 300,000 Vietnamese soldiers still not found, as official efforts to recover them has dragged amid funding shortfalls and limited DNA testing.
"We need support from the international community, including the American side," Le Thanh Tung, director of the Vietnamese Office for Seeking Missing Persons, which works with DPAA to help recover American remains.
"Cooperating with the US to search for American MIA remains in Vietnam is a way to mobilise US support to find Vietnamese martyrs," he told AFP.
In the absence of a coordinated national effort to find the bodies of Vietnamese fighters, some families turn to psychics to lead them to suspected death sites, or dig so-called empty graves so they have a place to worship the dead.
Johnson knows well the importance of having remains returned. Since her own father was repatriated and buried in Virginia, her family visits his grave a few times a year to lay flowers and give him updates on their lives.
Sitting in the DPAA office in Hanoi, next to a war-era Budweiser beer can, aftershave bottle and machine guns unearthed from past digs, Johnson described the feeling of helping American families whose relatives have been missing for decades.
"To know that we can help others feel complete, that's what makes this an amazing mission for me."