The defeat of France made the point, and the Tripartite Pact signed in Berlin in September 1940 provided the emphasis. Europe was Germany's; Japan was on the move in Asia, and there was a possibility that the United States might have to face a very hostile world alone, except for help from Canada and Latin America.

Arnold, showing his prescience, established a Strategic Air Intelligence Section in 1940. It was the first American attempt to develop economic, industrial and social analyses that would aid in target selection. Information came from unexpected quarters. The German electrical power grid, their petroleum industry and the synthetic oil plants had been financed in a major way by American banks. The conservative bankers had wanted to see what they were backing, and the Germans obligingly had furnished drawings and specifications, which were still in American bank vaults. That information also was valuable as a trading card, because the British needed it.

The trade was made; the British got US data, and the US got a large amount of British intelligence on the German aircraft and engine industries, transportation systems, and the Luftwaffe.

Early in 1941, British and American staff personnel held a series of informal talks. ABC-1, the report on those talks that was issued on 27 March 1941, summarized the common strategy that had been worked out in principle between Great Britain and the United States during those talks. The assumption by the US was that it would be facing Germany, Italy and Japan in any war. The prime American task would be defense of the Western Hemisphere, whereas Britain's would be the defense of the United Kingdom.

Since Germany was the predominant enemy, the main effort would be made against that country in Europe and the Atlantic. That effort would include a sustained air offensive. The air force's mission was to achieve superiority, particularly in the long-range striking forces. US bombardment units were to work closely in a combined offensive with the Royal Air Force, and their joint targets were to be found primarily in Germany.