Only a few months ago, UN and NATO officials were hailing a decline in Afghanistan’s opium crop and, therefore, a drop in the supply of the product that’s the raw ingredient of heroin. Closer reading of the data, though, showed that almost all the decline was the result of a fungus that blighted opium poppy plants. So the drop in supply was merely a temporary phenomenon, not a sign of progress in the war on drugs.

It turns out that the fungal blight may not provide even temporary benefits. Mohammad Ibrahim Azhar, Afghanistan’s deputy counter-narcotics minister, admits that while the poppy crop declined 48 percent in 2010, the price for the remaining crop nearly doubled. Understandably, Afghan farmers are rushing to plant additional opium poppies to take advantage of the financial bonanza.

This development comes as no surprise to experts who have studied the drug trade. Indeed, it should come as no surprise to anyone who understands basic economics, especially the nature of supply and demand. When demand for a product remains high, but the available supply drops, the price soars. That process applies to illegal drugs as much as it does to oil or any other commodity.

The great opium price spike of 2010–11 underscores the futility of U.S.-led antidrug efforts in Afghanistan and other countries. And yet the DEA is redoubling its heavy-handed presence in drug-source nations around the world, attempting to eradicate that lucrative trade. In the process, Washington’s drug warriors are alienating foreign populations and creating a new reservoir of enemies for the United States.

Both the international and domestic phases of the war on drugs are reminiscent of the story of Sisyphus in Greek mythology. The gods forever condemned Sisyphus to roll a large boulder up a hill in Hades only to have it roll down again. Officials in Afghanistan who are trying to curb the drug trade must especially feel a kinship with the unfortunate Greek. Despite all their efforts, Afghanistan is still the largest source (by far) of the world’s heroin supply. And new UN data show that the country has now become the principal source of hashish.

A prohibitionist strategy drives trade in a high-demand product underground, but it does not stop that trade. And by driving it underground, prohibitionism also creates vast new problems of violence and corruption. That is certainly evident in Mexico. It is equally apparent in Afghanistan, where the Taliban and al-Qaeda get an estimated $100 million to $400 million a year from the black-market commerce. Regional warlords and officials of the Karzai government also profit heavily.

One would think that after pursuing a prohibition strategy involving various illegal drugs (and for a time in the United States with alcohol as well) for nearly a century, policy makers would grasp the point that it doesn’t work. Sisyphus didn’t have a choice, but our political leaders do.