During the Vietnam war, US commanders grew increasingly concerned about the widespread use of drugs by US troops in Vietnam. Initially the focus was on marijuana. But in the early 1970s, reports began to emerge of the large scale use of heroin by US military personnel. The drug had became widely available in South Vietnam. Alex Last spoke to Dr Richard Ratner, then a psychiatrist in the US army in Vietnam, about his memories of treating soldiers suffering from heroin addiction.

Photo: Two soldiers in Vietnam exchange vials of heroin, July 1971 (Getty Images)