An unexplained technical fault is causing the Reaper drone to fall out of the sky, according to reports.
A Washington Post investigation found that electrical faults have caused a record 20 of the US Air Force's flagship drones to be destroyed or damaged in the last year, causing at least $2 million (£1.4m) of damages.
The problem has been traced to a faulty starter-generator, although invesigators haven't so far been able to work out why it keeps failing, documents released under the Freedom of Information Act show. The Post said:
"Military drones have slammed into homes, farms, runways, highways, waterways and, in one case, an Air Force C-130 Hercules transport plane in midair. No one has died in a drone accident, but the documents show that many catastrophes have been narrowly averted, often by a few feet, or a few seconds, or pure luck."
Over 400 large US military drones have crashed since 2011, with a number of different causes cited.
The documents show that one $3.8m (£2.6m) Predator crashed in Afghanistan because the pilot did not realise they'd been flying the aircraft upside down, whilst another incident was caused by a pilot pressing the wrong button on their joystick.
RAF Reaper drones are manufactured in the US. They're used for surveillance and airstrikes against Daesh targets in Iraq and Syria, with operators controlling them using computers on the ground.