(Column 1) (Column 2) 1 September 1939 Republic of Poland 9 April 1940 Kingdom of Norway 9 April 1940 Kingdom of Denmark 10 May 1940 Kingdom of Belgium 10 May 1940 Grand-Duchy of Luxembourg 10 May 1940 Kingdom of the Netherlands 6 April 1941 Kingdom of Greece 6 April 1941 Kingdom of Yugoslavia 22 June 1941 Union of Soviet Socialist Republics 11 December 1941 United States of America