The close-focusing lens and small size of the camera made it perfect for covert uses such as surveillance or document copying. The Minox was used by both Axis and Allied intelligence agents during World War II. Later versions were used well into the 1980s. The Soviet spy John A. Walker Jr., whose actions against the US Navy cryptography programs represent some of the most compromising intelligence actions against the United States during the Cold War era, used a Minox C to photograph documents and ciphers.