Some U.S. military drones operating above Syria have had their signals jammed by the Russian military, four U.S. officials told NBC News.
It began several weeks ago with some smaller U.S. drones in the wake of a series of suspected gas attacks on civilians in eastern Ghouta. The officials said the Russian military jammed the drones' GPS systems out of a concern the U.S. military would retaliate.
The officials said the jamming technology — blocking or scrambling signal to a device — is sophisticated. One U.S. official said the jamming is having an operational impact on military operations in Syria.
A Pentagon spokesman didn't say whether jamming is causing drones to crash: "The U.S. military maintains sufficient countermeasures and protections to ensure the safety of our manned and unmanned aircraft, our forces and the missions they support."