“The era of the Monroe Doctrine is over,” then-Secretary of State John Kerry told the Organization of American States in 2013. It was, like many foreign-policy declarations of the Obama years, gloriously optimistic and utterly wrong. 

President James Monroe’s declaration in 1823 that the U.S. would not permit the establishment of hostile powers in the Western Hemisphere has become the most famous idea in American foreign policy. The so-called Roosevelt Corollary of 1904 adds that if other nations in the Western Hemisphere default on their international obligations or endanger their neighbors through misgovernance, the U.S. has a “police power” to intervene.

Monroe’s original doctrine and Roosevelt’s extension have never been popular in Latin America, but U.S. presidents from Thomas Jefferson to Bill Clinton have taken an activist role in the region when they saw fit. 

Latin America policy has set off one firestorm after another in U.S. politics, especially during the Cold War. Notable examples include the Eisenhower-backed coup in Guatemala; the Kennedy administration’s Bay of Pigs fiasco; President Lyndon Johnson’s deployment of troops to the Dominican Republic; the Nixon administration’s opposition to Chile’s Marxist government ahead of the 1973 coup; and President Reagan’s Iran-Contra scandal.

Yet after the Cold War it seemed that U.S.-Latin American relations could relax. The fall of the Soviet Union reduced American concerns about Latin American leftism. Radical governments took power in countries like Ecuador, Bolivia and even Venezuela, but this didn’t prompt a vigorous American response. ...