<P> The alliance was formalised by the Declaration by United Nations, from 1 January 1942 . However, the name United Nations was rarely used to describe the Allies during the war . The leaders of the "Big Three"--the Soviet Union, the United Kingdom, and the United States--controlled Allied strategy; relations between the United Kingdom and the United States were especially close . The Big Three together with China were referred as a "trusteeship of the powerful", then were recognized as the Allied "Big Four" in the Declaration by United Nations and later as the "Four Policemen" of the United Nations . After the war ended, the Allied nations became the basis of the modern United Nations . </P> <P> The origins of the Allied powers stem from the Allies of World War I and cooperation of the victorious powers at the Paris Peace Conference, 1919 . Germany resented signing Treaty of Versailles . The new Weimar Republic's legitimacy became shaken . However, the 1920s were peaceful . </P> <P> With the Wall Street Crash of 1929 and the ensuing Great Depression, political unrest in Europe soared including the rise in support of revanchist nationalists in Germany who blamed the severity of the economic crisis on the Treaty of Versailles . By the early 1930s, the Nazi Party led by Adolf Hitler became the dominant revanchist movement in Germany and Hitler and the Nazis gained power in 1933 . The Nazi regime demanded the immediate cancellation of the Treaty of Versailles and made claims to German - populated Austria, and German - populated territories of Czechoslovakia . The likelihood of war was high, and the question was whether it could be avoided through strategies such as appeasement . </P> <P> In Asia, when Japan seized Manchuria in 1931, the League of Nations condemned it for aggression against China . Japan responded by leaving the League of Nations in March 1933 . After four quiet years, the Sino - Japanese War erupted in 1937 with Japanese forces invading China . The League of Nations condemned Japan's actions and initiated sanctions on Japan . The United States, in particular, was angered at Japan and sought to support China . </P>

Which of these nations was an ally of the united states during world war ii