Incoming flights heading to Heathrow airport were paused from landing this morning due to the RAF requesting use of its airspace.
Some flights were diverted to nearby hubs due to the delay in being able to land.
A Heathrow spokeswoman confirmed to the Standard that flights were now back to normal.
"Arrivals were paused briefly this morning due to an RAF request for an operational flight within part of Heathrow’s airspace," she said.
"Arrivals are now returning to normal.”
A Ministry of Defence spokesman confirmed it had coordinated a flight through the airspace.
He said: “The RAF can confirm that a flight was completed this morning by one of our assets from RAF Northolt, this flight was coordinated with Heathrow ATC but had to extend by a few minutes to complete its sortie. The minor delays caused to civilian air traffic are regretted.”
One person on a Heathrow bound flight said their "flight was circling for ages and crew saying something about security incident over Heathrow airspace."
Another said their pilot told them the airport was "closed for arrivals for a 'security incident'".