Security forces to test £1bn 'ring of steel' for Olympics

The water tower on an apartment block in Bow, east London, on which the MoD are planning to station high-velocity counter-terrorism missiles (EPA)

Inside a ring enforced by six ground-to air missile stations, RAF Typhoon jets will patrol the skies alongside naval helicopters carrying snipers from the Royal Marines, whose job will be to shoot down aircraft that refuse to turn back from the Olympic Park.

Almost £1bn is being spent on security for this summer's Olympics. This week, Londoners, and people at other venues such as Weymouth in Dorset, will see where their money is going – because a nine-day security training exercise for the Games begins tomorrow.

"The majority of this exercise will be played out in full view of the public," said the Defence Secretary, Philip Hammond. "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 – in Epping, Enfield, Blackheath, Greenwich, Bow and Waltham Forest – have been selected as temporary locations for air defence missile installations. The Ministry of Defence has assured residents that the military jets and helicopter gunships will cause only minimal disturbance during the test exercises, with "limited low flying".

The vast bulk of the security budget is being spent on wages for the personnel needed to ensure safety at the Games. Almost 20,000 security guards will be deployed, many of them volunteers. The figure includes 7,500 soldiers and naval personnel deployed in security roles.

Scotland Yard has refused to say how many armed police will be on duty during the Games, but it did confirm that military personnel would not be used on the streets of the capital.