Snipers, missiles and fighter jets over London: Get ready for a £1bn Olympic ring of steel

Inside a ring enforced by six ground-based missile stations, RAF Typhoon fast jets will patrol the skies, alongside navy helicopters carrying snipers from the Royal Marines, whose job it will be to shoot aircraft pilots who refuse to turn back from the Olympic Park.

Click here to see the 'How the games will be protected' graphic

Almost £1bn is being spent on security at the coming Olympics, and over the next week Londoners, and those at other venues such as Weymouth in Dorset, will get a look at what they are getting for their money.

A major nine-day training exercise testing the security plan for the Games begins tomorrow. It will see warships carrying helicopters stationed near Olympic venues, and fast jets patrolling flight paths through the capital.

"Support for the Olympic Games will be an important task for defence in 2012 and this exercise is about pushing our people and our systems to the limit to ensure that we are ready for the challenge," said the Defence Secretary, Philip Hammond. "The majority of this exercise will be played out in full view of the public and I hope it will have a secondary effect of reassuring the British people that everything possible is being done to ensure this will be a safe and secure Olympic and Paralympic Games."

Six sites, at Epping, Enfield, Blackheath, Greenwich, Bow and Waltham Forest are planned for installations of air defence missile systems. One, at Lexington Avenue in Bow, received attention over the weekend when residents expressed dissatisfaction at having notification of a missile system on their roof given to them by a note under the door.

The Ministry of Defence has also assured residents that the jets, helicopters and gunships will cause only minimal disturbance during the test exercises, with "limited low flying". The air defence systems will fire only practice drill missiles.

Residents at all the planned missile locations have reacted angrily to news of weaponry being installed in their neighbourhoods. "To hear there's going to be something capable of killing people that is going to be put on a block of flats a few minutes' walk from my house is shocking," said Flash Bristow, chairwoman of the Ferndale Area Residents Association in Waltham Forest.

The six selected sites are only provisional at this stage, but MoD officials hope they will be able to install the missiles at all of them. They also hope the heavy ordnance will not need to be deployed when the eyes of the world are on Stratford in the summer.

General Sir Nick Parker, who is in charge of operations for the Olympic and Paralympic Games, said: "We are practising for the worst-case scenario, not the most likely scenario, but we believe that it is prudent to be prepared."

The great bulk of the security costs will go on wages for the extra personnel who will be brought in. Almost 20,000 security guards will be deployed, many of them volunteers. The figure includes 7,500 soldiers and Navy personnel in security roles. Police have refused to say how many armed officers will be used during the Games, but they did confirm that military personnel would not be used on the streets.

The Metropolitan Police Assistant Commissioner, Chris Allison, who is the National Olympic Security Co-ordinator, insisted that no diplomatic staff or security officers from other countries, including the US, would be permitted to carry firearms during the games.

"The planning assumption is that there will be no other armed officers from across the world," he said. "The Games will be policed by the British police ... if there are any firearms required, it will be the British police who will be using their firearms."

Mr Allison confirmed that officers would not seek to clamp down on legitimate, peaceful protest during the Games, but stated that people did not have "the right to stop the Olympics happening, or the right to stop a torch bearer from having a once-in-a-lifetime opportunity, or the right to stop an athlete who has trained for years and years for their one chance of a gold medal".