The relations between the United States of America and the Union of Soviet Socialist Republics (1922–1991) succeeded the previous relations between the Russian Empire and the United States from 1776 to 1917 and precede modern-day relations between the Russian Federation and the United States that began in 1992. Full diplomatic relations between both countries were established in 1933, which was late due to the countries' mutual hostility. During World War II, both countries were briefly allies. At the end of the war, the first signs of post-war mistrust and hostility began to appear between the two countries, escalating into the Cold War; a period of tense hostile relations, with periods of détente.