 Successful testing of this combination led to the release of requirements to the aerospace industry for an air-to-surface missile on 15 July 1945.In March 1946 the USAAF began work on Project Mastiff, a nuclear armed air-to-surface drone or self-controlled air-to-surface missile.Northrop Corporation, Bell, and Republic Aviation were invited by the USAAF to submit proposals for Mastiff.