That was in a movie. Not sure if it was a real event. Severed arms in Vietnam.
“I did manage to get in touch with John Milius (via Francis Ford Coppola’s production company). Despite poor health following a stroke, Mr Milius was kind enough to reply to my email and say that the story of the Viet Cong atrocity was based on a real-life event recounted to him by a contact in Special Forces.
“This Special Forces source turned out to be Fred Rexer, who worked as military consultant on the film, was a Green Beret in Laos and took part in the Phoenix programme. He claims to have witnessed the event first hand (referenced in ‘The Apocalpyse Now Book’ by Peter Cowie).”