Foreign sources of opium are responsible for the entire supply of heroin consumed in the U.S. Efforts to reduce domestic heroin availability face significant problems. Unlike cocaine, which is concentrated in South America, opium production occurs in three source regions—Southeast Asia, Southwest Asia, and Latin America- creating a worldwide problem. While an undetermined amount of the opium is consumed in the producing regions, a significant amount of the drug is converted to heroin and sent to Europe and North America.
Historically, most of the world's illicit opium for heroin has been grown in the Golden Triangle of Southeast Asia. However, Latin America has emerged, in recent years, as the primary supplier of heroin to the United States. Colombian and Mexican heroin comprises 60 and 24 percent respectively of the heroin seized today in the United States. Low-level opium-poppy cultivation in Venezuela and even more limited growing in Peru currently produce only marginal amounts of heroin but could become the foundation for an expanding opium and heroin industry beyond Colombia. Opium-poppy cultivation in Venezuela is limited to the mountains opposite Colombia's growing area and appears to be a spillover from cultivation on the Colombian side of the border. Reports indicate that opium poppy cultivation in Peru over the last several years is nearly negligible.