A widely held view on the background and rationale of reform is that the international monetary system designed at Bretton Woods at the end of World War II served the world well for the first postwar generation, but that a new system is now required to cope with the changed requirements of the 1970s and beyond. It follows from this approach that the amendments required in the new system should be based on the evolving changes that have taken place in the structure of the world economy. The most important of these changes has been the diffusion of economic strength among at least the major countries, with a corresponding decline in the relative economic strength of the United States.