Declassified US records reveal the nation's intelligence chiefs used hundreds of Nazis as spies and informants after World War Two.
Central Intelligence Agency officials are said to have turned to the country's former enemies to help beat the Soviet Union during the Cold War.
Academics studying the documents say America used at least 1,000 ex-Nazis.
Some had served at the highest levels of the Nazi Party, and were recruited to work as spies for the US in Europe.
Former SS officer Otto von Bolschwing reportedly wrote policy papers on how to terrorise Jews, but was hired by the CIA to spy in Europe after World War Two.
The agency is said to have relocated him and his family to New York in the 1950s as a reward for loyal service.
Nazi collaborator Aleksandras Lileikis - linked to the massacres of tens of thousands of Jews in Lithuania - was recruited by the US as a spy in East Germany and later brought over to Boston.
There is evidence the CIA even tried to intervene when Mr Lileikis became the subject of a war crimes investigation.
The recruitment of Nazi assets occurred against the backdrop of Cold War paranoia and panic.
But records indicate long-time FBI director J Edgar Hoover not only approved of the use of ex-Nazis as spies, he also dismissed the horrific acts they had been involved in during the war as Soviet propaganda.
The revelations come one week after an Associated Press investigation found the US government had paid dozens of suspected Nazi war criminals millions of dollars in Social Security benefits after forcing them to leave the US.
The payments were made through a legal loophole. The US justice department later said benefits are paid to individuals who renounce US citizenship and leave voluntarily.