The Pentagon has given US military bases permission to shoot down or otherwise destroy consumer drones flying overhead and nearby.
A spokesman revealed that guidance was issued on 4 August.
He said the exact terms of the policy were classified.
The move comes days after the US Army ordered its own troops to stop using drones made by Chinese manufacturer DJI because of alleged “cyber-vulnerabilities”.
It became illegal to fly personal drones within 400ft (122m) of the US’s 133 military facilities in April.
The Federal Aviation Administration announced at the time that those who disobeyed the order would face financial penalties and possible criminal charges.
The watchdog has forecast that US-based hobbyists will own more than 3.5 million drones by 2021, and that there could be a further 1.6 million commercial models in operation.
The technology’s growing popularity has raised privacy and safety concerns.
There have already been incidents in which members of the public have shot down drones flying over their own properties.
And the new guidance is intended to clarify what steps military bases can take, and warn local communities of the potential counter-measures.
“We retain the right of self-defence and when it comes to… drones operating over military installations, this new guidance does afford us the ability to take action to stop those threats,” Navy Captain Jeff Davis said in a written statement, adding that this included “tracking, disabling and destroying” the aircraft.
The US Army’s ban on DJI drones was first reported on 2 August by the SUAS News website.
It published a memo revealing that the armed forces had been told to cease all use of the Shenzhen-based firm’s drones, to uninstall its applications and to disconnect any storage media from its devices.
DJI is the best-selling drone brand in North America, according to Skylogic Research. The firm indicated the development had caught it by surprise.
“We do not market our products for military customers, and if military members choose to buy and use our products as the best way to accomplish their tasks, we have no way of knowing who they are or what they do with them,” said a spokesman.
“The US Army has not explained why it suddenly banned the use of DJI drones and components, what ‘cyber-vulnerabilities’ it is concerned about, or whether it has also excluded drones made by other manufacturers.”
The US Army had little to add on the matter.
“We can confirm that guidance was issued; however, we are currently reviewing the guidance and cannot comment further at this time,” a spokesman said.
The UK’s Ministry of Defence told the BBC it had not purchased any of DJI’s drones and had nothing further to add on the subject.