The United States is not exactly happy about Beijing's drone proliferation. But, in this one case, it's been strangely helpful.

The United States is still by far the world's leader in the field of military drones, with hundreds of high-tech, missile- and bomb-armed robot aircraft and thousands of smaller, unarmed models deployed across the planet.

But China is catching up fast. And now we can confirm that Beijing's remote-controlled warplanes have had their combat debut—in a seemingly unlikely place. A social media post seems to verify what observers have suspected since January: China's killer robots are at war in Nigeria, apparently helping Abuja's military battle the deadly Boko Haram extremist group, which controls much of northeastern Nigeria and has kidnapped and enslaved hundreds of girls.

The first evidence that the Nigerian air force had gotten its hands on Chinese-made unmanned aerial vehicles came on Jan. 27 this year, when Twitter users in Nigeria's Borno state, in the war-torn northeast, posted photos of what appeared to be a crashed drone.

And not just any drone. The wreckage matched the profile of a CH-3—boomerang-shaped, roughly 25 feet from wingtip to wingtip and powered by a rear-mounted "pusher" propeller. Capable of flying an estimated 12 hours at a time at a cruising speed of around 150 miles per hour, the camera-equipped CH-3 is a "a capable system. Not cutting edge, but capable," according to Peter W. Singer, a drone expert at the New America Foundation and the author of several books, including the newly-released Ghost Fleet.

Most surprisingly, the crashed drone in Borno was packing a pair of what looked like AR-1 air-to-ground missiles under its wings. The January Tweets were the first indication ever that armed Chinese drones had flown in combat. America's own unmanned aerial vehicles, or UAVs, have been flying strike missions since late 2001.

China Aerospace Science and Technology Corporation, which makes the CH-3, did not respond to an email seeking confirmation of the CH-3 sighting. Nor did the Nigerian air force. On July 24, Nigerian news outlet Naija247news posted a story online featuring several photos of Air Vice Marshal Sadique Baba Abubakar, a top air force official, visiting a military airfield in Yola in northeast Nigeria.

One of the photos depicts Abubakar inspecting—you guessed it—a CH-3 drone.

To be sure, Chinese officials have been saying for years that they would happily sell UAVs to, well, pretty much anyone—meeting a demand for robotic warplanes that the United States refuses to satisfy. Export laws bar American companies such as General Atomics, which manufactures the iconic Predator and Reaper, from selling to many countries.