The steel-gray U.S. Air Force Predator drone plunged from the sky, shattering on mountainous terrain near the Iraq-Turkey border. For Kurdish guerrillas hiding nearby, it was an unexpected gift from the propaganda gods.

Fighters from the Kurdistan Workers' Party (PKK) filmed the charred wreckage Sept. 18 and uploaded a video on YouTube. A narrator bragged unconvincingly that the group had shot down the drone. But for anyone who might doubt that the flying robot was really American, the video zoomed in on mangled parts stamped in English and bearing the label of the manufacturer, San Diego-based General Atomics.

For a brief moment, the crash drew back the curtain on Operation Nomad Shadow, a secretive American military surveillance program. Since November 2011, the U.S. Air Force has been flying unarmed drones from Turkey's Incirlik Air Base, a joint U.S.-Turkish military installation, in an attempt to suppress a long-simmering regional conflict.