Vietnamese plaintiffs have condemned a US court's decision to dismiss their legal action against manufacturers of Agent Orange during the Vietnam War.
Former soldier Nguyen Van Quy says he will not stop campaigning
"It is a wrong decision, unfair and irresponsible," said Nguyen Trong Nhan, vice president of Vietnam's Association of Agent Orange (VAVA).
He said his group was thinking of filing an appeal.
The judge in the case said allegations the chemical caused birth defects and illness had not been proved.
"There is no basis for any of the claims of plaintiffs under the domestic law of any nation or state or under any form of international law. The case is dismissed," said US District Judge Jack B Weinstein.
But Mr Nguyen disagreed.
"Weinstein has turned a blind eye before the obvious truth. It's a shame for him to put out that decision. We just want justice, nothing more.
"This is just another war that could be long and difficult, as was the Vietnam War. We are determined to pursue it until the very end, until the day we will be able to ask for justice," he said.
Former North Vietnamese solder Ngyuen Van Quy, who is being treated for liver and stomach cancer and whose two children are disabled, also said he would not give up his struggle for compensation.
"I'll fight, not just for myself, but for millions of Vietnamese victims. Those who produced these toxic chemicals must take responsibility for their action," he said.
The plaintiffs had sought compensation from pharmaceutical firms including Monsanto, Dow Chemical and Hercules Incorporated, for the alleged effects of Agent Orange, a defoliation agent used to deprive communist Vietnamese forces of forest cover.
The plaintiffs argued that the chemical caused birth defects, miscarriages and cancer.
The civil action was the first attempt by Vietnamese plaintiffs to claim compensation for the effects of Agent Orange.
The defendants argued that the US government was responsible for how the chemical was used, not the manufacturers.
However, in 1984, several chemical companies paid $180m (£93m) to settle a lawsuit with US war veterans, who said that their health had been affected by exposure to the substance.
Ngo Thanh Nhan, a professor who participated in a campaign to drum up support for the case, said this fuelled the Vietnamese plaintiffs' argument.
"If the medical files [of Vietnamese victims] are not convincing enough, we will use the ones of the American soldiers," he said in Tuoi Tre newspaper.
"There's no reason why those who sprayed chemical products got compensation for their contamination... and the direct victims' suit is rejected by an American court."
Agent Orange was named after the colour of its container. As well as herbicides which stripped trees bare, it contained a strain of dioxin.
In time, some contend, the dioxin entered the food chain and caused a proliferation of birth defects.
Some babies were born without eyes or arms, or were missing internal organs.
Activists say three million people were exposed to the chemical during the war, and at least one million suffer serious health problems today.