This is an index of lists detailing military conflicts involving the United States, organized by time period.
Although the United States has formally declared war only five times and these declarations cover a total of 11 separate instances against specific nations, there are currently 204 non-colonial military conflicts included in these lists, 7 of which are ongoing. Between all seven lists, there are currently 243 military conflicts.
Formal declarations of war include the War of 1812 (United Kingdom), the Mexican–American War (Mexico), the Spanish–American War (Spain), World War I (Germany and Austria-Hungary) and World War II (Japan, Germany, Italy, Bulgaria, Hungary and Romania).
Since World War II, the U.S. has engaged in numerous military operations authorized by Congress or initiated by the executive branch without formal declarations of war; notable examples include the Cold War (the Korean War, the Vietnam War, and the Gulf War), the War on terror (the War in Afghanistan and the War against ISIS), and interventions aimed at regime change (the Iraq War, Libya, and the Iran War).World Book Encyclopedia, 2025 ed., s.v. "War"
As of the current date, the United States is involved in 7 publicly known military engagements across 6 different wars. Wars with direct U.S. involvement include War on terror (Somalia and Yemen), the war on cartels (Operation Southern Spear), and the Iran War. Wars with indirect U.S. involvement include the Russo-Ukrainian war (U.S. involvement), the Gaza war (U.S. involvement), and the Israel–Hezbollah conflict.
Lists 1609–1700 List of 17th-century wars involving the Thirteen Colonies Summary: Native American confederacies stood as the primary opponents to English expansion, defining this period through early survival conflicts with colonists, such as the Anglo-Powhatan Wars in Virginia and the Pequot War in Southern New England. As colonial populations rapidly grew, the friction escalated into devastating regional struggles like King Philip's War, a conflict that resulted in a higher per-capita casualty rate than any other war in Colonial American history and ultimately ended in a defeat for the Native Americans, leaving the tribes permanently weakened and unable to stop colonial expansion. 1701–1774 List of 18th-century wars involving the Thirteen Colonies Summary: The Thirteen Colonies were drawn directly into a series of major European power struggles transposed onto North American soil, where imperial rivalries between Kingdom of Great Britain, Kingdom of France, and Spanish Empire played out across the wilderness frontiers. Conflicts like Queen Anne's War and King George's War forced American colonists to organize local militias and fight alongside British soldiers, binding the fate of the colonies tightly to European geopolitics. The era culminated in the French and Indian War (the North American theater of the Seven Years' War) which placed British forces and their colonial allies against the French and various Native American nations. By removing the French threat and giving local militias vital combat experience, this victory left the colonies newly empowered and highly self-reliant. 1775–1800 List of wars involving the United States in the 18th century Summary: The American Revolutionary War successfully secured United States independence from the British Empire. Following the revolution, the new nation immediately faced localized conflicts as it sought to stabilize its fragile economy, assert federal authority over its frontiers, and protect its borders. These efforts led to the Northwest Indian War against a confederation of Native American tribes to secure western territorial expansion. At the same time, the United States sought to secure its commercial interests overseas by forming a permanent navy, which immediately engaged in undeclared maritime warfare such as the Quasi-War against France. 1801–1850 List of wars involving the United States in the first half of the 19th century Summary: The first half of the 19th century featured the War of 1812 against Great Britain, which solidified American sovereignty, alongside the Barbary Wars to defend shipping interests in the Mediterranean Sea. This era also saw extensive internal conflicts, including the Seminole Wars and the implementation of the Indian Removal Act, which forcibly displaced Native American tribes westward of the Mississippi River. The period concluded with the Mexican–American War, which drastically expanded the nation's boundaries to the Pacific Coast via the Mexican Cession, a treaty agreement in which Mexico ceded roughly 55 percent of its pre-war territory. 1851–1900 List of wars involving the United States in the second half of the 19th century Summary: The second half of 19th century was dominated by the American Civil War, the bloodiest conflict in United States history, which preserved the Union and abolished slavery. The late 1800s were also characterized by the ongoing American Indian Wars in the West and the expansionist Spanish–American War, which resulted in the acquisition of Guam, Puerto Rico, and the Philippine Islands from Spain, while establishing temporary control over Cuba, that secured the long-term lease of Guantánamo Bay. By the end of the century, the United States further extended its reach by annexing the Hawaiian Islands following the overthrow of the Hawaiian Kingdom. 1901–2000 List of wars involving the United States in the 20th century Summary: After the final engagements of the American Indian Wars in the early 1900s, the 20th century emerged as the costliest and bloodiest era for the nation in foreign conflicts. As its domestic frontiers closed, the United States increasingly turned its attention outward, expanding its geopolitical influence across the Atlantic and Pacific oceans. During the century, major interventions in World War I and World War II transformed the United States into a global superpower. These pivotal victories led to the eventual fall of traditional global empires, the defeat of fascism in Europe, and the collapse of Japanese imperialism, concluding with the historic first operational use of nuclear weapons at Hiroshima and Nagasaki. In the middle of the 20th century, the newly formed CIA began conducting covert operations globally. The subsequent Cold War was defined by the persistent threat of nuclear conflict and the containment of communism, drawing the American forces into major Asian campaigns, most notably the Korean War and the deeply polarizing Vietnam War. U.S. military efforts directly influenced regional borders and governance, such as the preservation of South Korea's independence, the safeguarding of Taiwan's autonomous status, and the restoration of Kuwaiti sovereignty. Among the high-profile foreign figures the United States targeted or helped depose were Adolf Hitler, Benito Mussolini, Isoroku Yamamoto, Hideki Tojo, Che Guevara, Hudson Austin, Manuel Noriega, Raoul Cédras, and Slobodan Milošević. 2001–present List of wars involving the United States in the 21st century Summary: Following the September 11 attacks, the United States launched the global War on Terror. This campaign involved significant military operations in the Middle East, such as the War in Afghanistan and the Iraq War. Operations later expanded into complex counter-insurgency campaigns alongside international coalitions against al-Qaeda, ISIS, Al-Shabaab and others, accompanied by a widespread expansion of global drone strike campaigns. The United States targeted and helped overthrow high-profile figures and militant leaders worldwide, including Osama bin Laden, Ayman al-Zawahiri, Anwar al-Awlaki, Abu Musab al-Zarqawi, Abu Ayyub al-Masri, Akhtar Mansur, Baitullah Mehsud, Abu Bakr al-Baghdadi, Abu Ibrahim al-Hashimi al-Qurashi, Ahmed Abu Khattala, Joseph Kony, Saddam Hussein, Muammar Gaddafi, Bashar al-Assad, Nicolás Maduro, Qasem Soleimani, and Ali Khamenei.
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