The United States reacted to World War II similarly to how it reacted to World War I. Initially, America remained neutral for two years until it entered the war on December 8, 1941, after the Pearl Harbor bombing. The country had been moving towards alliances with Allied powers over the years. The events that led to the war in Europe included the Treaty of Versailles and Germany's desire for revenge, economic downturns, rise in extremism, and failure of appeasement.