In his testimony before the Senate Foreign Relations Committee (April 23, 1971), Kerry charged that American soldiers had “raped, cut off ears, taped wires from portable telephones to human genitals and turned up the power, cut off limbs, blown up bodies, randomly shot at civilians, razed villages, shot cattle and dogs for fun, poisoned food stocks and generally ravaged the countryside of Vietnam.”
Although the article doesn't mention it, Kerry cited, in his Senate testimony, the "Winter Soldier Investigation" as his main evidence for American atrocities.
Several of the witnesses in the WSI have suffered exposure as frauds. Kerry has never, to my knowledge, had to defend the truth of the WSI testimony.