The term 'OLD CRUISE MISSILE' can be broken down into two crossword solutions: NAVAHO (6 letters) and OCM (3 letters). NAVAHO is a type of cruise missile developed by the United States during the Cold War. It was the first operational surface-to-surface missile in the US arsenal, and was used for both nuclear and conventional warfare. OCM stands for 'Old Cruise Missile', which was the designation given to the NAVAHO missile after it was retired from service in the late 1970s.