What is the full name for the alliance system formed by the US an Western European nations after World War 2?

There were various alliances following WW11. The United Nations was formed in part from FDR. He believed the strict punishments against Germany after WW1 led to Hitler's aggressive state which could have been mediated if there was a outlet for Hitler to address his grievances. Also, the North Atlantic Treaty Organization was formed as military alliance of European nations and the U.S. against the communist Soviets.