ABC-1

The U.S.–British Staff Conference was a series of secret discussions between United States and British military staff members on American, British and Canadian (ABC) military coordination in the event of U.S. entry into World War II. The conference took place in Washington, D.C. from January 29, 1941 to March 27, 1941 and concluded with a report entitled "ABC-1" which was tacitly approved by the President two days later.

The US-British Staff Conference Report of 1941 established the general military principles, resources, and deployment strategies for a joint Allied military strategy. The plan assumed that if the U.S. went to war with Germany, it would likely go to war with both Italy and Japan as well. The general principles of agreement stated that:

Offensive policies included:

Finally, if Japan entered the war, military strategy in the Far East would be defensive. Although the ABC-1 agreement was not a military alliance, it nevertheless signified that the United States was preparing to enter the war on the side of the Allied powers, that the United States would make every effort to maintain the security of the British Commonwealth, and that the United States military was modifying existing war plans (e.g. the RAINBOW plans) to incorporate military integration and cooperation with other nations.

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