The policy is classified. A military spokesperson said the order went out in July and that it details what over 130 bases should do when drones enter their airspace.
Officials say the policy was a response to the surging popularity of drones. The Federal Aviation Administration, which worked on the ruling, estimates consumers and businesses will buy and fly at least 7 million drones by 2020. And currently, civilians don't need to register their drones with the U.S. government.
Some rules are vague. The policy specifically applies to drones that it says are potential "threats," but the military didn't say when or how a drone becomes a threat.
And many military bases are on leased land, so it could be unclear who owns the airspace and if the rules even apply.
For now, bases can act "upon the specific circumstances" and deal with the problem however they see fit.