Question: when was the last time the us formally declared war
Answer: ay , Japanese Instrument of Surrender ( September 2 , 1945 ) , Treaty of San Francisco ( September 8 , 1951 ) Declaration of War upon Germany Germany December 11 , 1941 88 -- 0 393 -- 0 V-E Day , German Instrument of Surrender ( May 8 , 1945 ) , Treaty on the Final Settlement with Respect to Germany ( September 12 , 1990 ) , Treaty of Vienna with Austria ( May 15 , 1955 ) Declaration of War upon Italy Italy 90 -- 0 399 -- 0 Paris Peace Treaty ( February 10 , 1947 ) Declaration of War upon Bulgaria Bulgaria June 5 , 1942 73 -- 0 357 -- 0 Declaration of War upon Hungary Hungary 360 -- 0 Declaration of War upon Romania Romania 361 -- 0