The illegal drug trade led to the growth of an enormously wealthy and powerful criminal establishment centered initially in Medellín and Cali. In the late 1980s, under increasing pressure from the United States, Colombian governments began to crack down on these drug traffickers, threatening to extradite them to the United States, where punishment was both more effective and more severe than in Colombia.

In response, the head of the Medellín drug cartel, Pablo Escobar, unleashed a bombing campaign that killed hundreds of civilians in Colombia’s major cities. Drug money was also behind the assassinations of three presidential candidates in 1990. The Constitution of 1991 prohibited extradition, but the Colombian government reinstated it soon thereafter. Escobar was eventually apprehended and killed in 1993.

By the late 1990s Colombia’s drug war had shifted toward efforts to eradicate coca, plants that are used to make cocaine, and poppies, flowers that are used to make opium. In 1999 the Colombian government announced Plan Colombia, a program to decrease the cultivation of coca and poppies in areas of southeastern Colombia largely controlled by the FARC. The following year the United States announced that it would give $1.3 billion in aid, primarily for military hardware such as helicopters and planes, to support aerial fumigation of coca and poppy fields.

Critics of the plan claimed that the spraying was dangerous to human health and the environment, that the small farmers who grew the coca had no viable economic alternatives, and that the plan’s real purpose was to aid the Colombian military in its battle against the guerrillas. Supporters of Plan Colombia denied these allegations and claimed fumigation would significantly reduce coca cultivation. Early data indicated that Colombian coca production continued to rise. Encarta