The table below lists the instances in which a state has declared war against the United States. It is interesting to note that on several occasions, when a foreign power has declared war, the United States has not formally reciprocated with such an action.
War
Declaration
Opponent(s)
Date of declaration
President
Result
style="white-space:nowrap;"Boxer Rebellion
[[https://en.wikipedia.org/wiki/Imperial_Decree_of_declaration_of_war_against_foreign_powers
Qing dynasty
June 21, 1900
Mexican–American War
"An Act providing for the Prosecution of the existing War between the United States and the Republic of Mexico."[1]
Mexico
May 13, 1846
40–2
173–14
James K. Polk
Treaty of Guadalupe Hidalgo (February 2, 1848)
Spanish–American War
Declaration of War upon Spain
Spain
April 25, 1898
42–35
310–6
William McKinley
Treaty of Paris (December 10, 1898)
World War I
Declaration of War upon Germany
Germany April 6, 1917
82–6
373–50
Woodrow Wilson
Treaty of Berlin (August 25, 1921)
Declaration of War upon Austria-Hungary [2] [3] Austria-Hungary
December 7, 1917
74–0
365–1
1921 U.S.–Austrian Peace Treaty (August 24, 1921), 1921 U.S.-Hungarian Peace Treaty (August 29, 1921)
World War II
Declaration of War upon Japan
Japan December 8, 1941
82–0
388–1
Franklin D. Roosevelt
V-J Day , 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[2]
Hungary 360–0
Declaration of War upon Romania[2]
Romania 361-0
