This was the British and US air power agreement reached by military leaders at the 'Arcadia' first Washington conference (29 January/27 March 1941).

The plan established that the USA would undertake the development of a 54-group air force for hemisphere defence while preparing for the development of a 100-group air force for offensive operations, but that until such time as the USA entered the war, primary allocation of aircraft from new production capacity would go to the UK, and then be split evenly between the UK and USA after the latter’s entry into the war.