Safety concerns were raised after two RAF Tornado jets reported a drone within 500ft of their flight path over Dunbar.
The jets were at 1,500ft when they spotted the remote-controlled aircraft.
The Air Proximity Board noted the incident as a “conflict of airspace” but said the pilots had assessed the risk of collision as “low”. The drone operator has not been traced.
The RAF said there was “considerable concern” about the proliferation of drones.
“The proliferation of small unmanned aircraft (SUA) and the difficulty in policing the regulations in terms of operating areas and altitudes, continues to raise considerable concern within the military flying community.
“The formal investigation of this Airprox found that the only active barrier to mid-air collision was the use of lookout by the Tornado crews and the SUA operator.”