London: British military commanders said they were training to deal with a "9/11-type attack" as they launched a major exercise today to test their readiness for the 2012 London Olympics.
As jet fighters took to the sky with nine weeks to go to the opening ceremony, the Olympic Park was getting its biggest try-out as the final wave of sporting test events got under way.
Four Royal Air Force (RAF) Typhoon fighter jets flew into the British capital to herald the start of Exercise Olympic Guardian, a nine-day training operation to test the response to a possible air attack during the Games.
Military helicopters were stationed around the capital, including on the amphibious assault ship HMS Ocean in the River Thames, with some carrying sniper teams.
AWACS surveillance planes and air-to-air refuelling aircraft will also be airborne during the exercise.
Airspace restrictions will be in place throughout the July 27-August 12 Games.
Air Vice-Marshal Stuart Atha, air component commander for Olympics air security, said their plan had several levels and "will allow us to deal at one end -- which is that 9/11-type attack -- perhaps down to the lower and the slower type of threat that we may face.
"All we are doing is having in place what we would describe as prudent and appropriate measures, in order that we could react if required in a timely and appropriate fashion."
Speaking of any potential attackers, he added: "I would hope when they see how we are preparing they might be deterred from making any threats to the Games."
Typhoons are stationed on high alert as part of Britain`s regular air defence.
"Whilst there is no specific threat to the Games, we have to be ready to assist in delivering a safe and secure Olympics for all to enjoy," said Defence Secretary Philip Hammond.
The exercise underlines the commitment "to keeping the public safe at a time when the world will be watching us".
At the Olympic Park in Stratford, east London, five venues were to stage events in three Olympic and three Paralympic sports between Wednesday and next Tuesday.
Assisted by 11,000 staff, more than 140,000 spectators were to watch 3,000 athletes take part in hockey, wheelchair tennis, water polo, athletics, boccia and Paralympic athletics.