They were indeed. While I am no expert on Operation Paperclip's specifics, the famous rocket scientist Wernher von Braun (responsible for the Saturn V rocket), was picked up through this, along with many of the other scientists that worked on the Nazi V2 programme. It was done in order to ensure that this valuable new technology would fall into the hands of the Soviet Union. von Braun, while never 100% confirmed, did know about the conditions at a Concentration Camp that manufactured the V2 rockets. Michael Neufeld certainly makes the accusation that von Braun personally picked slave labour for his rockets. Regardless of these debated points of history, it is fact that Wernher von Braun was a member of the National Socialist Party, along with the vast majority of German rocket scientists, most of whom came to America to work in the Defense Department and NASA. Names such as Kurt Debus, Dieter Huzel, and Arthur Rudolph join von Braun among former Nazis that worked with the American government, some of them included in Operation Paperclip.

Source: Von Braun: Dreamer of Space, Engineer of War by Michael J. Neufeld

Related: did the USSR or other countries have their own programs to import Nazi scientists?