During the Games an aircraft carrier will dock on the Thames. Surface-to-air missile systems will scan the skies. Unmanned drones, thankfully without lethal missiles, will loiter above the gleaming stadiums and opening and closing ceremonies. RAF Typhoon Eurofighters will fly from RAF Northolt. A thousand armed US diplomatic and FBI agents and 55 dog teams will patrol an Olympic zone partitioned off from the wider city by an 11-mile, £80m, 5,000-volt electric fence.