Monroe Doctrine

The Monroe Doctrine is a U.S. foreign policy stance that rejects outside interference in the Western Hemisphere. Initially aimed at European colonialism, it states that any foreign power meddling in the Americas could be seen as a hostile act toward the United States. This policy became a key part of American grand strategy during the 1900s.

President James Monroe first laid out the doctrine on December 2, 1823, in his seventh annual message to Congress, though it wasn’t called the Monroe Doctrine until 1850. At that time, most Spanish colonies in the Americas had either gained independence or were close to it. Monroe declared that the New World and the Old World should stay separate spheres of influence, and any further European efforts to control or influence independent nations in the region would threaten U.S. security. In return, the U.S. promised to recognize existing European colonies, not interfere with them, and stay out of Europe’s internal affairs.

Because the U.S. lacked a strong navy and army when the doctrine was announced, European colonial powers largely ignored it. The United Kingdom helped enforce it in part, using it to support its own Pax Britannica policy, but the doctrine was disregarded several times in the 1800s—most notably during the second French intervention in Mexico. By the early 1900s, a turning point in U.S. foreign policy, the United States itself could finally enforce the doctrine. It has since been cited by many U.S. leaders, including presidents Ulysses S. Grant, Theodore Roosevelt, John F. Kennedy, Ronald Reagan, and Donald Trump.

After 1898, lawyers and intellectuals reinterpreted the Monroe Doctrine as promoting multilateralism and non-intervention. In 1933, under President Franklin D. Roosevelt, the U.S. reinforced this view by helping create the Organization of American States. Into the 2000s, the doctrine continues to be denounced, revived, or redefined in various ways.

The roots of the Monroe Doctrine go back to the early days of the United States. According to historian Samuel Eliot Morison, the U.S. adopted a policy of isolation as early as 1783, declaring it would stay out of Europe. The idea that Europe should stay out of America came later. Even though the U.S. started as an isolationist country, the groundwork for the doctrine was laid soon after the American Revolution. Alexander Hamilton, writing in *The Federalist Papers*, wanted the U.S. to become a world power strong enough to keep European powers out of the Americas, even though European nations then controlled far more territory there than the U.S. did. Hamilton expected the U.S. to dominate the New World and eventually act as a go-between for Europe and new American nations.

James Madison, then Thomas Jefferson’s secretary of state, expressed U.S. opposition to further European land grabs in a note to the ambassador to Spain. This sentiment may have carried little weight, since European powers held much more land than the U.S. at the time. Though Jefferson favored France, his administration made clear to U.S. ambassadors that the country would not support any future colonization in North America, aiming to keep the U.S. out of European conflicts.

The U.S. feared that the victorious powers from the Congress of Vienna (1814–1815) would restore monarchies. France had already agreed to return the Spanish monarchy in exchange for Cuba. As the Napoleonic Wars ended, Prussia, Austria, and Russia formed the Holy Alliance to defend monarchism, authorizing military action to reestablish Bourbon rule in Spain and its colonies, which were winning independence.

British foreign policy aligned with the Monroe Doctrine’s goals. Britain secretly helped South Americans fight Spain and offered to issue a joint statement on the doctrine, worried that further European colonization would harm trade with the Americas. For many years after the doctrine was announced, Britain—through its Royal Navy—was the only power enforcing it, since the U.S. Navy was small. The U.S. declined a joint statement due to the recent War of 1812, but the immediate trigger was the Russian Ukase of 1821, which claimed the Pacific Northwest and barred non-Russian ships from its coast.

The full Monroe Doctrine, mostly written by future president and then secretary of state John Quincy Adams, is lengthy and diplomatic, but its core appears in two key passages. The first declares that the New World is no longer open to European colonization: “The occasion has been judged proper for asserting, as a principle in which the rights and interests of the United States are involved, that the American continents, by the free and independent condition which they have assumed and maintain, are henceforth not to be considered as subjects for future colonization by any European powers.” The second key passage expands on this stance.