The ongoing U.S. presence in Afghanistan is plenty misguided on its own: our efforts likely increase rather than decrease Muslim antipathy toward the United States, and our track record of fostering democracy, capitalism, peace, or freedom via invasion and occupation is, to say the least, poor.

To make matters worse, we are complicating the mission by also trying to suppress opium production:

The United States spent more than $7 billion in the past 14 years to fight the runaway poppy production that has made Afghan opium the world’s biggest brand.

Beyond the usual arguments, American-inspired drug prohibition is especially problematic in Afghanistan. The inevitable evasion and corruption undermine the rule of law, and anti-opium actions such as crop eradication generate hostility from local farmers rather than winning their hearts and minds.

Not to mention that all our efforts appear to have no meaningful impact on the opium trade:

More opium was cultivated in 2014, the last year of the NATO combat mission, than in any other year since the United Nations began keeping records in 2002.

The good news is that, despite U.S. efforts, the opium trade is normalizing:

But here in one of the few corners of Helmand Province that is peaceful and in firm government control, the green stalks and swollen bulbs of opium were growing thick and high within eyeshot of official buildings during the past poppy season — signs of a local narco-state administered directly by government officials.

In the district of Garmsir, poppy cultivation not only is tolerated, but is a source of money that the local government depends on. Officials have imposed a tax on farmers practically identical to the one the Taliban use in places they control.

Some of the revenue is kicked up the chain, all the way to officials in Kabul, the capital, ensuring that the local authorities maintain support from higher-ups and keeping the opium growing. And Garmsir is just one example of official involvement in the drug trade.

Multiple visits to Afghan opium country over the past year, and extensive interviews with opium farmers, local elders, and Afghan and Western officials, laid bare the reality that even if the Western-backed government succeeds, the opium seems here to stay.

To be sure, official prohibition combined with de facto legalization is far from the libertarian ideal.

But de facto tolerance for the opium trade allows farmers to earn a living in peace and saves the resources now wasted on attempts at opium suppression. Permitting the market to move above ground also shrinks the violence associated with underground markets.

Profits from opium trafficking are, of course, a source of revenue for terrorists. That, however, is also an artifact of prohibition: if opium were legal, the profit rate would be no different than for any other crop, and terrorists would have one less source of revenue.