President James Monroe’s 1823 annual message to Congress contained the Monroe Doctrine, which warned European powers not to interfere in the affairs of the Western Hemisphere.

The United States has always taken a particular interest in its closest neighbors—the nations of the Western Hemisphere. Expressions of this concern have not always been favorably regarded by other American nations.

The Monroe Doctrine is the best known U.S. policy concerning the Western Hemisphere. Buried in an annual message delivered to Congress by President James Monroe in December 1823, the doctrine warns European nations that the United States would not tolerate further colonization or puppet monarchs. The doctrine was conceived to meet major concerns of the moment, but it soon became a watchword of U.S. policy in the Western Hemisphere.

The Monroe Doctrine was invoked in 1865 when the U.S. government exerted diplomatic and military pressure in support of the Mexican President Benito Juárez. This support enabled Juárez to lead a successful revolt against the Emperor Maximilian, who had been placed on the throne by the French government.

Almost 40 years later, in 1904, European creditors of a number of Latin American countries threatened armed intervention to collect debts. President Theodore Roosevelt promptly proclaimed the right of the United States to exercise an “international police power.” As a result, U. S. Marines were sent into Santo Domingo in 1904, Nicaragua in 1911, and Haiti in 1915, ostensibly to keep the Europeans out. Other Latin American nations viewed these interventions with misgiving, and relations between the “great Colossus of the North” and its southern neighbors were strained for many years.

In 1962, the Monroe Doctrine was invoked symbolically when the Soviet Union began to build missile-launching sites in Cuba. With the support of the Organization of American States, President John F. Kennedy threw a naval and air quarantine around the island. After several tense days, the Soviet Union agreed to withdraw the missiles and dismantle the sites. Subsequently, the United States dismantled several of its obsolete air and missile bases in Turkey.

Source: Monroe Doctrine (1823)
U.S. National Archives & Records Administration