1970s: Colombia becomes one of the international centers for illegal drug production and trafficking. Drug cartels virtually control the country, which provides 75 percent of the world's cocaine.

Today: The United States invests $3 billion into “Plan Colombia,” a joint U.S.-Colombia coca antinarcotics plan, which started in 2000. Officials claim that as of 2005 the program has eradicated more than a million acres of coca plants, but Colombian drug traffickers still manage to supply 90 percent of the cocaine used in the United States—the same percentage supplied when the program began.

1970s: Marxist guerrilla groups organize against the Colombian government, most notably, the May 19th Movement, the National Liberation Army, and the Revolutionary Armed Forces of Colombia. They plunge the country into violence and instability.

Today: The United Nations declares that Colombia is suffering the worst humanitarian crisis in the Western Hemisphere. More than two million...