The position of United States Ambassador to Australia has existed since 1940. U.S.–Australian relations have been close throughout the history of Australia. Before World War II, Australia was closely aligned with the United Kingdom, but it has strengthened its relationship with the United States since 1942, as Britain's influence in Asia has declined and the United States' influence has increased. At the governmental level, United States–Australia relationships are formalised by the ANZUS treaty and Australia-United States Free Trade Agreement.