We owe it, therefore, to candor and to the amicable relations existing between the United States and those powers to declare that we should consider any attempt on their part to extend their system to any portion of this hemisphere as dangerous to our peace and safety. With the existing colonies or dependencies of any European power we have not interfered and shall not interfere. But with the Governments who have declared their independence and maintain it, and whose independence we have, on great consideration and on just principles, acknowledged, we could not view any interposition for the purpose of oppressing them, or controlling in any other manner their destiny, by any European power in any other light than as the manifestation of an unfriendly disposition toward the United States.
James Monroe (1758–1831), U.S. president. seventh annual message to Congress, Dec. 2, 1823. The Monroe Doctrine.
The Monroe Doctrine was formulated with the help of John Quincy Adams and formed the basis of U.S. foreign policy in the ambit of central and South America. Theodore Roosevelt's corollary in 1904 that disturbances in Latin America might compel U.S. intervention to preempt European involvement was invoked by presidents Taft and Wilson to justify operations in the Caribbean.