The Monroe Doctrine was a United States policy of opposing European colonialism in the Americas beginning in 1823. ... 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.
Explanation:
The strategy of "containment" is best known as a Cold War foreign policy of the United States and its allies to prevent the spread of communism after the end of World War II.