In 1954, when France gave up Indochina, the United States decided to sponsor a friendly client state in South Vietnam, led by Ngo Dinh Diem. American troops would not leave South Vietnam until 19 years later — two years after which point the country fell to the North. Now a similar denouement may be nearing for the American involvement in Afghanistan, which began nearly 18 years ago.

Ngo Dinh Diem seemed to establish fairly firm control over Vietnam during his first few years, but a renewed Communist guerilla offensive beginning in 1959 put him under great pressure and exposed his lack of support even among non-Communists. A coup overthrew him in 1963 and by 1965 South Vietnam was about to fall to the Communists. Rather than negotiate a settlement, President Johnson sent combat troops in, and by 1969, they numbered more than half a million men.

Richard Nixon — and, with him, Henry Kissinger — came into office in that year committed to the objective of maintaining a non-Communist South Vietnam. But they also found, after another year of heavy fighting, that the public demanded a reduction in the scale of U.S. involvement. As American troop levels declined in the next few years, the South Vietnamese government — now under Nguyen van Thieu — seemed to be doing much better. But in early 1972, when nearly all the U.S. combat troops were gone, the North Vietnamese launched a huge offensive and occupied significant portions of the country before U.S. air power managed to halt the offensive.