The United States has been involved in hundreds of interventions in foreign countries throughout its history, engaging in nearly 500 military interventions between 1776 and 2026, with half of these operations occurring since 1950 and over 25% occurring in the post-Cold War period. Common objectives of U.S. foreign interventions have historically revolved around economic opportunity, protection of U.S. citizens and diplomats, territorial expansion, counterterrorism, fomenting regime change and nation-building, promoting democracy, providing aid and enforcing international law. There have been two dominant ideologies in the United States regarding foreign policy—interventionism, which encourages economic, political and military intervention in the affairs of foreign countries—and isolationism, which discourages these.Wertheim, "Tomorrow The World," 2020, p4.

The 19th century formed the roots of United States foreign interventionism, which at the time was largely driven by economic opportunities in the Pacific and Spanish-held Latin America along with the Monroe Doctrine, which saw the U.S. seek a policy to resist European colonialism in the Western Hemisphere. The 20th century saw the U.S. intervene in two world wars in which American forces fought alongside their allies in international campaigns against Imperial Japan, Imperial and Nazi Germany, and their respective allies. The aftermath of World War II resulted in a foreign policy of containment aimed at preventing the spread of world communism. The ensuing Cold War resulted in the Truman, Eisenhower, Kennedy, Carter, and Reagan Doctrines, all of which saw the U.S. engage in espionage, regime change, proxy wars, and other clandestine activity internationally against affiliates and puppet regimes of the Soviet Union. The Nixon Doctrine reaffirmed the nuclear umbrella but wanted U.S. allies to be self-dependent, as exemplified by Vietnamization.

After the Soviet Union collapsed in 1991, the U.S. emerged as the world's sole superpower and, with this, maintained interventionist policies in Africa, Eastern Europe, and the Middle East. Following the September 11 attacks in 2001, the Bush administration launched the "war on terror" in which the U.S. waged international counterterrorism campaigns against various extremist groups—such as al-Qaeda and the Islamic State—in various countries. The Bush Doctrine of preemptive war saw the U.S. invade Afghanistan in 2001 and Iraq in 2003. In addition, the U.S. expanded its military presence in Africa and Asia via status of forces agreements and a revamped policy of foreign internal defense.

The Obama administration's Pivot to Asia strategy sought to refocus U.S. geopolitical efforts from counter-insurgencies in the Middle East to bolstering U.S. influence in East and Southeast Asia, reinforcing the first island chain and countering China's rising influence and perceived expansionism in the South China Sea —a trajectory continued by the Trump (2017–2021, 2025–present) and Biden administrations under the Free and Open Indo-Pacific (FOIP) strategy. The second Trump administration introduced the Trump Corollary to the Monroe Doctrine, aiming to consolidate U.S. dominance in the Western Hemisphere and prevent Chinese, Russian and other adversarial powers from meddling in "America's backyard." In January 2026, the U.S. intervened in Venezuela, capturing President Nicolas Maduro and constraining his government. The next month, the United States and Israel jointly attacked Iran, killing Iranian supreme leader Ali Khamenei and other Iranian leaders, sparking the ongoing 2026 Iran war.

The United States Navy serves as a key element of United States global power projection and its ability to conduct foreign interventions. As a blue-water navy, it has been involved in anti-piracy activity in international and foreign territory throughout its history, from the Barbary Wars to combating modern piracy off the coast of Somalia and other regions. The United States Air Force's strategic airlift and global strike capabilities alongside clandestine activity by special operations units are two other major components in U.S. hard power projection.

Post-colonial

The 18th-19th century saw the United States transition from an isolationist, post-colonial regional power to a Trans-Atlantic and Trans-Pacific maritime power. From 1790 to 1797, the U.S. Revenue Marine served as the United States' only armed maritime service, tasked with enforcing export duties, and was the predecessor to the United States Coast Guard. The 1794 Naval Act authorized the construction of the first six frigates of what would subsequently become the permanent United States Navy. Throughout the century, the United States increasingly engaged in gunboat diplomacy to intimidate less powerful entities and fulfill foreign policy objectives. President James K. Polk was an advocate of American expansionism under Manifest Destiny and saw U.S. territory reach the Pacific Ocean, setting the foundations for future U.S. power projection and interventionism.

The first and second Barbary Wars of the early 19th century were the first nominal foreign wars waged by the United States following independence. Directed against the Barbary States of North Africa, the Barbary Wars were fought to end piracy against American-flagged ships in the Mediterranean Sea, similar to the undeclared "Quasi-War" with the French Republic from 1798 to 1800. The founding of Liberia was privately sponsored by American groups, primarily the American Colonization Society, but the country enjoyed the support and unofficial cooperation of the United States government.Flint, John E. The Cambridge History of Africa: from c.1790 to c.1870 Cambridge University Press (1976) pg 184-199

Notable 19th century interventions included: 1803–1860: The United States purchases the Louisiana territory from France in 1803, expanding its sovereignty west of the Mississippi River and nearly doubling the nominal size of the country across North America. The treaty of 1818 establishes a boundary along the 49th parallel north between Rupert's Land and the U.S. In 1853, the U.S. purchases 29,640-square-mile (76,800 km2) of land from Mexico, defining the Mexico–United States border. 1811: U.S. federal agent Joel Roberts Poinsett arrives in Chile to assess the prospects of Chilean revolutionaries during their war against the Spanish Empire, leading the first of many U.S. interventions in Chile. 1846–1848: During the Mexican–American War, Mexico and the United States warred over Texas, California, and what today is the American Southwest but was then part of Mexico. During this war, U.S. Armed Forces troops invaded and occupied parts of Mexico, including Veracruz and Mexico City. 1854: Commodore Matthew C. Perry negotiated the Convention of Kanagawa, which effectively ended Japan's centuries of national isolation, opening the country to Western trade and diplomacy. From 1863 to 1864, U.S. forces participated in the Shimonoseki campaign, a conflict over Japan's open-door policy as a result of Perry's expedition. 1854–1949: The U.S. Navy launches the Yangtze Patrol in 1854, an operation to protect U.S. interests, merchant ships and citizens in China's Yangtze river treaty ports and along China's coast. The mission was permanently ended in 1949 amid the Chinese Civil War. 1858–1859: President James Buchanan dispatched a diplomatic mission and nineteen-ship squadron to Paraguay under the auspices of seeking reparations for previous Paraguayan aggression against U.S. citizens. 1871: The U.S. dispatched an expeditionary force to Korea after failed attempts to ascertain the fate of the armed merchant ship General Sherman, which was attacked during an unsuccessful attempt to open up trade with the isolationist kingdom in 1866. After being ambushed, the 650-man American expeditionary force launched a punitive campaign, capturing and occupying several Korean forts and killing over 200 Korean troops. 1887–1889: U.S. and German naval forces engaged in a months-long standoff over control of the Samoan Islands during the Samoan Civil War. The standoff ended when a cyclone wrecked all six ships involved. The 1899 Tripartite Convention partitioned the islands into American Samoa and German Samoa. 1898: The short but decisive Spanish–American War saw overwhelming American victories at sea and on land against the Spanish Kingdom. The U.S. Army, relying significantly on volunteers and state militia units, invaded and occupied Spanish-controlled Cuba, subsequently granting it independence. The peace treaty saw Spain cede control over its colonies of Puerto Rico, Guam, and the Philippines to the United States. The U.S. Navy set up coaling stations there and in Hawaii.William Braisted, United States Navy in the Pacific, 1897–1909 (2008) See also: Bath Iron Works 1899: The U.S. advanced the Open Door Policy to guarantee equal economic access to China and support of Chinese territorial and administrative integrity.

The early decades of the 20th century saw a number of interventions in Latin America by the U.S. government often justified under the Roosevelt Corollary to the Monroe Doctrine. President William Howard Taft viewed Dollar diplomacy as a way for American corporations to benefit while assisting in the national security goal of preventing European powers from filling any possible financial power vacuum. The Small Wars Manual outlined the role U.S. Marines served as an expeditionary force to project power and police countries in the U.S.'s sphere of influence. Marines were often deployed to safeguard customs revenues which were the cause of local civil wars.Lester D. Langley, The Banana Wars: United States Intervention in the Caribbean, 1898–1934 (2001) 1898–1935: The U.S. launched multiple minor interventions (Banana Wars) into Latin America, resulting in U.S. military presence in Cuba, Honduras, Panama (via the Hay–Bunau-Varilla Treaty and Isthmian Canal Commission), Haiti (1915–1935), the Dominican Republic (1916–1924), and Nicaragua (1912–1925; 1926–1933). 1901: The Platt Amendment amended a treaty between the U.S. and the Republic of Cuba after the Spanish–American War, virtually making Cuba a U.S. protectorate. The amendment outlined conditions for the U.S. to intervene in Cuban affairs and permitted the United States to lease or buy lands for the purpose of the establishing naval bases, including Guantánamo Bay. 1904: When European governments began to use force to pressure Latin American countries to repay their debts, Theodore Roosevelt announced his "Corollary" to the Monroe Doctrine, stating that the United States would not just prevent but militarily intervene in affairs between European and Latin American governments if European pressure resulted in the Latin countries becoming chronically unstable failed states. 1906–1909: The U.S. governed Cuba under Governor Charles Magoon. 1914: During a revolution in the Dominican Republic, the U.S. Navy fired at revolutionaries who were bombarding Puerto Plata, in order to stop the action. 1916 to 1924: U.S. Marines occupied the Dominican Republic following 28 revolutions in 50 years. The Marines ruled the nation completely except for lawless parts of the city of Santo Domingo, where warlords still held sway. 1899–1901: The U.S. organized the China Relief Expedition during the Boxer Rebellion, which saw an eight-nation alliance put down a rebellion by the Boxer secret society and toppled the Qing dynasty's Imperial Army.