Operation Paperclip was the code name for the 1945 Office of Strategic Services, Joint Intelligence Objectives Agency recruitment of German scientists from Nazi Germany to the U.S. after VE Day. President Truman authorized Operation Paperclip in August 1945; however he had expressly ordered that anyone found "to have been a member of the Nazi party and more than a nominal participant in its activities, or an active supporter of Nazism militarism" would be excluded. Under this criterion many of the scientists recruited, such as Wernher von Braun, Arthur Rudolph and Hubertus Strughold, who were all officially on record as Nazis and listed as a "menace to the security of the Allied Forces," were ineligible.
All were cleared to work in the U.S. after having their backgrounds "bleached" by the military. The paperclips that secured newly-minted background details to their personnel files gave the operation its name. Following the failure of the German invasion of the Soviet Union, Germany was at a disadvantage since its military industries were unprepared for a long war.
As a result, Germany began efforts in Spring 1943 to recall scientists and technical personnel from combat units for use in research and development, including 4000 to rocket work:
One of the biggest travesties of justice in history; Nazi scum being brought to the US and given asylum, all of their war crimes expunged so they could work for us developing technology.