By the end of 1944, U.S. forces had captured a fair number of Italian and German soldiers from the North Africa, Italian, and Normandy campaigns. Many of these POWs were shipped back to the U.S. for detention (carried in empty ships that had brought troops and material to Europe). Once in the states, the military police realized they had to separate out the hard-core Nazis. It was quite effective and was implemented within the bounds of the Geneva Conventions. Good for the Army for figuring out the same for Iraq.