After a decade of reconstruction and over $7 billion spent on counternarcotic operations, the results are in: the United States has lost the “war on drugs” in Afghanistan, although few U.S. officials are willing to admit it. According to this report from the Special Inspector General for Afghanistan Reconstruction (SIGAR), poppy cultivation is actually at an all-time high, over 8 percent higher in 2013 than the previous peak in 2007.

And, with the United States slated to reduce its presence in Afghanistan, the problem is likely to get worse. According to the report, given the “deteriorating security in many parts of rural Afghanistan and low levels of eradication of poppy fields, further increases in cultivation are likely in 2014.”

Some observers are more optimistic, however. A letter from the U.S. embassy in Kabul states that the United States is “making good progress in building the capacity of [its] Afghan partners to design, lead, manage, and sustain over the long term strategic and tactical counternarcotics efforts addressing all stages of the drug trade.”

It’s difficult to understand their optimism. The embassy letter, which is included in the SIGAR report, admits that “poppy cultivation has shifted from areas where government presence is broadly supported and security has improved, toward more remote and isolated areas where the governance is weak and security is inadequate.”

Looking ahead, however, unless one believes—contrary to all evidence—that Afghan government control will expand into these areas as the U.S. military presence shrinks, that should translate to more poppy cultivation, not less. The embassy curiously refused to come to that conclusion.

Washington’s war on drugs in Afghanistan, like its war on drugs in the Americas, tries to defy the most basic law of economics: supply and demand. And it’s having tragic effects, as my colleague Ted Galen Carpenter has observed for years (including especially here and here). So long as the world’s appetite for drugs remains high, willing sellers will be there to satiate it.

It is hardly surprising that a prohibitionist strategy didn’t work in Afghanistan. It is surprising that some thought it would, or still might, given that it has failed everywhere else.