Showing photos of the tumours that had been removed from her abdomen and throat, Mo could not utter a word during the tearful reunion with her friend in Ho Chi Minh City's outlying Cu Chi District last week.

Nga had not recognised her close friend, though they sat near each other. Someone in the room had to tell her it was Bay Mo (the name the guerrilla soldier had used during the war).

Time and the defoliants that had been sprayed during the war four decades ago had taken their toll on Mo, once known as the most beautiful soldier in Cu Chi.

Now 70, Mo said the tumours had been caused by her exposure to the chemical.

As a soldier living in the Cu Chi Tunnels, the then-teenager at times had to eat rats to stay alive underground. But she was smart and healthy, and she sometimes took part in battles fought in the narrow, foul-smelling passages.

Tran To Nga (left) talks to two French lawyers while she visits the former Dong Du Military Base in Cu Chi with an American film crew and Vietnamese journalists. — VNS Photos Van Dat

She also blew up two US tanks.

During the war, her friend Nga worked as a correspondent for the Liberation News Agency, now Vietnam News Agency.

Nga was based in Cu Chi, where dioxin was sprayed by US troops to destroy foliage cover to make it easier to spot the enemy.

Those who lived in the area only knew that the spray was a kind of weedkiller.

Nga, who moved to France after the war and has French nationality, said her lawyers Amelie Lefebvre and Bertrand Repold, who were with her in Cu Chi, would file a lawsuit in France against 26 American companies that manufactured the chemical, known as Agent Orange, used during the war.

The agent contained2,3,7,8-trach-lorodibenzodioxin (TCDD), an extremely toxic dioxin compound. "This is the last chance," she said.

During the war, Nga said she had to write her news stories in the tunnels.

Emerging periodically from her underground post, she sometimes spotted planes dropping bombs. But one day she did not hear any sound but only saw a white cloud-like streak in the air.

"The planes left after they released the powdery carpet from the sky. It quickly came down to the forest," Nga recalled.

Nga said she began to cough and develop a fever. Her skin became itchy.

"Like others, I thought the chemical was only an herbicide, and did not know that it contained dioxin," she said.

Defective heart

She stayed and worked in the forest for years, unaware of the danger. She gave birth to her first child, who had a defective heart and died when she was 17 months old.

"I had not thought that her death was caused by Agent Orange. For 30 years, I believed that I brought death to my daughter. Doctors say that my second daughter, who has had several miscarriages, might develop blood cancer later," she said.

Over the years, Nga has met several people exposed to Agent Orange. The images of mothers with powerless eyes holding their children crying and squirming on the floor have never left her mind.

They are the motivation behind her lawsuit.

Tran To Nga (left) talks to two French lawyers while she visits the former Dong Du Military Base in Cu Chi with an American film crew and Vietnamese journalists. — VNS Photos Van Da

Hours before the tearful reunion with Mo and other Cu Chi guerrillas, Nga visited a site near the former Dong Du Military Base, where the traces of bombs and Agent Orange remain.

Trees grew everywhere except on the site where she visited. It was covered only with grass and weeds.

Nga was excited to see that the river in the area was still there.

During wartime, she bathed in its water, drank from it and cooked with it, not knowing that it had been contaminated with dioxin.

"I didn't know that I was being exposed to Agent Orange at that time. We innocently had our bodies exposed without knowing what it really was and its harmful consequences," Nga said.

At the site, Nga met Dang Hong Nhut, who had joined the resistance force against the US. She was also heavily exposed to Agent Orange.

Nhut said she and others during the war had cooked fish taken from the river.

"We knew that the fish had died from some kind of chemical. We thought we could eat the fish as long as they were cooked well. We ate wild vegetables there, too," she said.

The 79-year-old, who has had several miscarriages, recalled the atmosphere of the war as she stood near a hole created by a bomb.

"There was no day or moment without sounds of bombs and gunfire," she said.

The trees had lost their leaves and only tattered clothes hung on them, a result of explosions that had killed soldiers, she said.

"I remember a day in 1965 when I was in Tay Ninh. I hid because I knew a plane was coming. I was surprised because it had not released bombs as usual. The sky became dark. I found a kind of powder on the leaves," Nhut said.

"I had heard that some kind of chemical weapon existed, but at that time I thought the people exposed to it would die immediately," she said. "I didn't know that it could remain in the body for decades and affect younger generations."

On the same day, Nhut and Nga, along with the two French lawyers, visited a local family who lived just steps away from the dioxin-infected site. There, they met Nguyen Hoang Lan, who was born in the area in 1969, a time of fierce fighting.

His son, Nguyen Hoang Nhan, 18, who is known for his intelligence, has a deformed right ear and has undergone surgery. Lan's other son, Nguyen Le Hau, 13, can barely talk, and sat still in his chair during the group's visit.

Lan's wife quit her farm work to stay at home to take care of Hau. Lan, who works as a security guard for a local company, is the sole breadwinner of the family.

Dioxin-sprayed areas

Cu Chi is not the only Agent Orange hot spot in Vietnam. It is estimated that 19 million gallons of herbicides were sprayed over 4.5 million acres of land in Vietnam between 1961 and 1970.

In 2012, the US government started cleaning up dioxin-affected areas in Danang. The Danang airbases were among the most toxic of 28 dioxin hot spots in Vietnam.

Environmental remedies have also been deployed at Bien Hoa Airport. Other former air bases are expected to be cleaned up within the next decade, erasing the most toxic traces of dioxin.

"The disease my children have to suffer for the rest of their life cannot be corrected," said Lan, who only realised he had been affected by AO after his second son was born.

He said he did not know where and when he was exposed to the chemical. Lan's only concern now is earning enough money to support and feed his family.

As he spoke, near the treeless plot of land where Agent Orange had been sprayed during the war, cows nibbled the grass and the river quietly flowed.