Bangladesh, Nov. 13 -- Afghanistans opium fields are withering, and with them a major pillar of the global narcotics economy. According to the latest United Nations Office on Drugs and Crime (UNODC) survey, poppy cultivation has fallen drastically since the Talibans nationwide ban, reshaping regional trafficking patterns and driving price volatility across South and Central Asia.

The Taliban, for its part, has hailed this collapse as proof of restored order and moral discipline. If the ban holds, it will represent in fact one of the most effective counternarcotics measures in modern history — something the NATO occupation never managed, in two decades.

However, sudden contraction in the worlds most profitable illicit commodity may...