The Monroe Doctrine was a United States policy that opposed European colonialism in the Americas. It argued that any intervention in the politics of the Americas by foreign powers was a potentially hostile act against the United States. It began in 1823; however, the term "Monroe Doctrine" itself was not coined until 1850.
The Monroe Doctrine was issued on December 2, 1823, at a time when nearly all Latin American colonies of Spain had achieved, or were at the point of gaining, independence from the Spanish Empire. It stated that further efforts by various European states to take control of any independent state in the Americas would be viewed as "the manifestation of an unfriendly disposition toward the United States." At the same time, the doctrine noted that the U.S. would recognize and not interfere with existing European colonies nor meddle in the internal affairs of European countries.
President James Monroe first stated the doctrine during his seventh annual State of the Union Address to the Congress. The doctrine asserted that the New World and the Old World were to remain distinctly separate spheres of influence. The separation intended to avoid situations that could make the New World a battleground for the Old World powers so that the U.S. could exert its influence undisturbed. By the end of the 19th century, Monroe's declaration was seen as a defining moment in the foreign policy of the United States and one of its longest-standing tenets. The intent and effect of the doctrine persisted for more than a century, with only small variations, and would be invoked by many U.S. statesmen and several U.S. presidents, including Ulysses S. Grant, Theodore Roosevelt, John F. Kennedy, and Ronald Reagan.
After 1898, the Monroe Doctrine was reinterpreted in terms of multilateralism and non-intervention by Latin American lawyers and intellectuals. In 1933, under President Franklin D. Roosevelt, the U.S. went along with this new reinterpretation, especially in terms of the Organization of American States.