There is a growing tension between two U.S. objectives in Afghanistan. The most important objective is—or at least should be—the eradication of the remaining Al Qaeda and Taliban forces in that country. But the United States and its coalition partners are now also emphasizing the eradication of Afghanistan’s drug trade. These antidrug efforts may fatally undermine the far more important anti-terrorism campaign.

Like it or not, the growing of opium poppies (the source of heroin) is a huge part of Afghanistan’s economy—roughly half of the country’s annual gross domestic product. As long as the United States and other drugconsuming countries pursue a prohibitionist strategy, a massive black market premium exists that will make the cultivation of drug crops far more lucrative than competing crops in Afghanistan or any other drugsource country. For many Afghan farmers, growing opium poppies is the difference between prosperity and destitution. There is a serious risk that they will turn against the United States and the U.S.-supported government of President Hamid Karzai if Washington and Kabul pursue vigorous anti-drug programs. In addition, regional warlords who have helped the United States combat Al Qaeda and Taliban forces derive substantial profits from the drug trade. They use those revenues to pay the militias that keep them in power. A drug eradication campaign could easily drive important warlords into alliance with America’s terrorist adversaries.

Even those Americans who oppose drug legalization and endorse the drug war as a matter of general policy should recognize that an exception needs to be made in the case of Afghanistan. At the very least, U.S. officials should be willing to look the other way regarding the opium crop and recognize that the fight against radical Islamic terrorists must have a higher priority than anti-drug measures.