Updated 12:15 p.m., December 30

This might be the only measurement you need to judge the Afghanistan War. Vendors in Kabul are doing a brisk trade in Taliban ringtones. Because Afghans report that the Taliban kill travelers at clandestine checkpoints if they don't hear one of their messages on someone's phone.

Purchasers don't necessarily want their phones to trill with the auto-tuned chant below, or with the dulcet melodies of "Suicide Bomber." (Sample translated lyric: "You burned like a moth, young hero.") They worry they won't be safe on the roads if they can't play the track for the Taliban when the insurgents stop their vehicles, checking for loyalty. Travelers approaching Taliban checkpoints often pop their real SIM cards out and replace them with ones containing insurgent-produced jingles none of their contacts.

"If they search your phone and see your videos and songs, they will think you are their sympathizer," a 35-year-old Kabul grocer, Haji Mohammad Khan, explains to the Wall Street Journal. "On occasion, it can save your life."

The growth in Taliban ringtones is a sign that after 10 years of war and a surge of U.S. troops, the U.S. and its allies still don't control Afghanistan's countryside. The big brains at Darpa even set up a quasi-intelligence program, called Nexus 7, to suss out the war's progress by studying obscure metrics like the stability of fruit prices. But you don't need Nexus 7's spreadsheets and data sets to know that if Afghans have to pose as Taliban sympathizers, you're losing.

And there isn't much opportunity for the U.S. to turn things around. The surge troops are coming home by next summer. Holding territory after taking it from the Taliban is last year's endeavor. These next few years are about getting barely competent Afghan cops and soldiers ready to wage the war on their own. Meanwhile, Afghanistan's east remains buckwild – and, as the Journal reports, even the areas around the capitol of Kabul are reverting to Taliban control.

And while the Taliban's ringtones echo from Afghan Nokias and Samsungs, Washington is reverting to a backup plan: courting the Taliban with secret diplomacy to end the war. Taliban leader Mullah Omar signaled a few months ago that he was open to those talks.

Who knows if the talks will yield a peace deal. In the meantime, the Taliban – already adept at texting death threats, tweeting its propaganda, and trolling the Americans – crank out about a dozen new ringtones every month for public consumption.

The Taliban's version of Black Ark Studios reportedly hosts a stable of 40 singers with "beautiful and attractive voices" whose songs provide a "lesson in bravery, manliness and protecting the country from the invaders," Taliban spokesman Zabihullah Mujahid told the Journal. Plus, if you don't carry their ringtones, they'll kill you.