Lincolnshire RAF Typhoons 'on call' for the Olympics
Four Typhoon aircraft normally based in Lincolnshire are on call for the Olympics.
The RAF said the aircraft from RAF Coningsby have been stationed at Northolt in Middlesex since Tuesday.
It also said they could be called at short notice to intercept unidentified aircraft around the Olympic sites.
Sqn Ldr Gordon Lovett said: "There is no specific threat to the Games, but we have to be ready for all eventualities."
The RAF said it was the first time fighter aircraft had conducted operations from the airfield since World War II.
It said the fighter jets, which had recently been used in Libya, were one part of a "multi-layered air security plan to protect the London Games".