The outcome of the war had a profound effect on the course of world history. The old European empires collapsed or were dismantled as a direct result of the wars' crushing costs and, in some cases, their fall was caused by the defeat of imperial powers. The United States became firmly established as the dominant global superpower, along with its ideological foe, the Soviet Union, in close competition. The two superpowers exerted political influence over most of the world's nation-states for decades after the end of the Second World War. The modern international security, economic, and diplomatic system was created in the aftermath of the wars.