The primary force behind rocket development in the US space program was Wernher von Braun. Von Braun was a German rocket scientist who was brought to the United States after World War II as part of Operation Paperclip. He worked for the US Army Ballistic Missile Agency and later NASA, where he was responsible for developing the Saturn V rocket that took the first humans to the moon. Von Braun is considered one of the fathers of modern rocketry and his work laid the foundation for the US space program.