1812 — Great Britain

The War of 1812 hinged on international trade disputes and U.S. expansion.

1846 — Mexico

Following the Mexican-American War over territory, the U.S. annexed eight western states.

1898 — Spain

The U.S. entered into the Spanish struggle with Cuba over independence.

1917 — Germany

After remaining neutral for several years, the U.S. joined World War I.

1917 — Austria-Hungary

Involvement in WWI quickly deepened when the U.S. went to war with Germany’s ally.

1941 — Japan

A spectacular air attack on Pearl Harbor spurred the U.S. to enter World War II.

1941 — Germany

The U.S. responded in kind after Germany declared war first.

1942 — Bulgaria,

Hungary, Romania

The three German allies first declared war against the U.S.


In many cases, presidents have asked Congress to pass legislation allowing or supporting the use of military force:

1798 — France

The fledgling U.S. Navy was ordered to protect American trading ships from the French.

1802 — Tripoli

The Navy was again ordered to protect commerce ships from what is today Libya.

1815 — Algeria

Congress denied a presidential request for war but allowed Navy action to protect trade from this other North Africa country.

1819-23 — Caribbean, Latin America

Rampant pirating prompted a military response to protect U.S. merchant ships.

1955 — Formosa

The U.S. acted to fend off communist China from seizing the island now known as Taiwan.

1957 — Middle East

In the midst of the Cold War, Congress authorized military force if any countries in the region were attacked by communist forces.

1964 — Southeast Asia

Following the Gulf of Tonkin incident, combat forces were sent to Vietnam and elsewhere in the region.

1983 — Lebanon

U.S. Marines were sent to this Mid-East country bordering Syria to quell violence and provide stability.

1991 — Iraq

The U.S. pushed Iraqi forces out of Kuwait following an invasion and occupation.

2001 — Global

A global fight against the al-Qaida terrorist network and any countries helping them followed deadly attacks in New York, Washington and Pennsylvania.


Presidents have exerted executive power and used United Nations resolutions to wage military campaigns without first getting approval from Congress:

1950 — Korea

The U.S. sent air power and troops to the peninsula to repel invading communist North Korea forces backed by the Soviet Union.

1994 — Bosnia

The Clinton administration joined a NATO airstrike campaign to quell ethnic and religious fighting following a government disintegration.

Source: Congressional Research Service; American Journal of International Law

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