The Pentagon is to investigate charges that US forces used the deadly nerve gas, sarin, against defectors during the Vietnam War, although this was against official policy. The claim was made in a joint CNN/Time magazine investigation.
The Secretary of Defence, Mr William Cohen, said he was taking the charges seriously and had ordered the army, air force and service chiefs to carry out an inquiry.
Mr Cohen said the use of nerve gas in 1970 would have been against the policy laid down by President Nixon, who had "declared an end to the use of biological and chemical weapons". Sarin, also known as GB, was the gas used in an attack by a Japanese terrorist group in the Tokyo subway three years ago.
Veterans who took part in Operation Tailwind said on the programme that they attacked a village in Laos after a number of men suspected of being defectors had been spotted there. They spoke of as many as 20 American defectors leading about 140 enemy Montagnard guerrillas, most of whom were killed in the attack.
The veterans said nerve gas was used later against enemy troops to allow the US special forces unit to escape from the area. A former sergeant, Mike Hagen, who took part in the operation, said the government did not want to call it nerve gas. "They want to call it incapacitating agent or some other form but it was nerve gas."
A former lieutenant, Robert Van Busnik, who was a platoon leader in the operation, said on the programme: "It was pretty well understood that if you came across a defector, and could prove it to yourself beyond a reasonable doubt, do it, under any circumstance, kill them." He said: "It wasn't about bringing them back. It was to kill them."
A Pentagon spokesman had declined to comment, saying only the department had not had a chance to review the report. But another defence official was quoted as saying that although the air force had supplies of nerve gas in Vietnam, they were never used.
CNN and Time claim the gas was used in Operation Tailwind by US special forces hunting defectors hiding out in Laos. The report follows an eight-month investigation involving 200 interviews.
Admiral Thomas Moorer, chief of naval operations during the Vietnam War and a former chairman of the Joint Chiefs of Staff, told the programme Operation Tailwind was approved by President Nixon and the CIA. The report said Admiral Moorer confirmed the use of the nerve gas off-camera. During the interview he said he was "willing to use any weapon and any tactic to save the lives of American soldiers."
Pentagon officials have said they were aware of only "two confirmed defectors" in Vietnam. They also queried whether sarin would be effective in the heat of the jungle.