'Indigo' was a US contingency plan within the 'Color-coded War Plan' scheme for the occupation of Iceland, a Danish possession (1920s/1939).

This contingency planning was developed as 'Indigo III' for use in the movement of US forces to Iceland as replacements for the British forces at that time occupying the country since 'Fork' and 'Alabaster'. The first brigade of the US Marine Corps started to arrive on the island on 7 July 1941.