The Associated Press reports that 16 Afghan soldiers have just graduated from a new program at Fort Bliss that trained them to fly helicopters in drug eradication campaigns. They will now return to their homeland, the world’s top opium producer.

Washington’s increasing pressure on the government of Afghan President Hamid Karzai to wage a vigorous war on drugs is the latest installment in a prohibitionist strategy that has failed for decades. The international drug war is a terrible policy wherever it is tried, but it is an especially unwise venture in Afghanistan. As a recent Cato Institute policy study notes, the drug trade accounts for more than a third of that country’s economic output. Regional warlords who originally backed the Taliban and Al Qaeda but switched their allegiance to the Karzai government derive much of their revenue from the opium trade. Even more important, hundreds of thousands of Afghan farmers base their livelihood on drug crops. They will not look kindly on the Karzai government if it tries to drive their families into destitution.

U.S. policymakers need to keep their priorities straight. Our overriding objective in Afghanistan should be to eliminate the remaining Taliban and Al Qaeda forces. The drug war undermines that objective and may drive otherwise friendly Afghans into the arms of our enemies. There is a troubling correlation between the upsurge of violence in Afghanistan in recent months and the intensification of drug-eradication efforts during that same period. Indeed, the upsurge has been greatest in the main drug-producing provinces.

Even those Americans who remain wedded to a prohibitionist policy as a general principle ought to realize that an exception needs to be made in Afghanistan. Otherwise, the Taliban-Al Qaeda insurgency will grow, and we will replicate the Iraq debacle in that country, too.