The airport was already shut for more than 30 hours due to drone sightings. Flights had been operational for most of Friday prior to an evening disruption lasting around an hour.
Flights at London's Gatwick Airport were briefly halted again Friday evening due to a suspected drone flying near the area.
The precaution was taken for around an hour before flights resumed.
"Airfield movements were suspended while we investigated this as safety remains our main priority. The military measures we have in place at the airport have provided us with reassurance necessary to re-open our airfield," the airport said.
The shutdown came after London's second-busiest airport resumed operations on Friday morning, after flights were canceled for more than 30 hours when two drones were spotted near the airfield.
The disruptions have caused travel chaos during the busy Christmas season, with a number of flights scheduled to land since Wednesday being diverted to other airports. More than 120,000 passengers were affected.
Police described the drones as "unusually large" and said they may be operated deliberately in a bid to disrupt the airport at one of the busiest times of year.
It was unclear what Gatwick Airport meant by "military measures."
Detective Chief Superintendent Jason Tingley of Sussex Police told reporters on Thursday that shooting down drones was "one of the options" for removing the disruption.
cw/msh (AFP, AP, dpa, Reuters)