The Prime Minister will have his finger on the trigger as an unprecedented defensive 'ring of steel' is thrown up to protect London 2012.
The public will witness a show of military strength not seen at home since the Second World War.
The security in place to prevent a September 11-style atrocity or Mumbai-style terror attack as the eyes of the world are on London includes:
- State-of-the-art RAF Typhoon fighter jets loaded with fearsome weapons patrolling the skies over the Home Counties;
- A ring of six surface-to-air missile sites around London, each with the power to bring down rogue aircraft;
- The aircraft carrier HMS Ocean will be moored in the Thames with 800 Royal Marines;
- Seven Royal Navy Lynx and RAF Puma helicopters carrying crack snipers to target terrorists;
- HMS Bulwark, the Royal Navy's 21,000-tonne flagship, and other vessels deployed off Weymouth, Dorset, to protect sailing events;
- And 13,500 servicemen and women - more than are deployed in Afghanistan - on duty to keep the £9billion Olympics safe and secure.
General Sir Nick Parker, in charge of military operations during London 2012, revealed the unenviable task would rest at the 'highest political level'.
Mr Cameron possesses emergency powers to authorise the military to bring down planes or helicopters to stop an atrocity during this summer's sporting showcase.
News of Mr Cameron's role came as it was revealed that surface-to-air missiles could be deployed at six different sites across London during the Olympics.
The Lexington Building in Tower Hamlets and the Fred Wigg Tower in Waltham Forest, both in east London, have been identified as potential sites.
Blackheath Common and Oxleas Wood, both in south east London, plus William Girling Reservoir in the Lea Valley Reservoir Chain in Enfield and Barn Hill at Netherhouse Farm in Epping Forest are other possible sites.
The surface-to-air missiles will be deployed as the third tier of defence aimed at slower or smaller aircraft, and the final decision as to whether they will be fired will rest with Mr Cameron.
The six sites are all potential locations for ground-based air defence systems, should the Government decide to deploy them during the Games.
Residents in the private, gated flats next to the Lexington Building Water Tower in Bow have received a leaflet warning them that a team of ten soldiers and police will be placed at the building – home to 700 people – for the duration of this summer’s Games.
It follows an announcement by Defence Secretary Philip Hammond in November that missiles might be used to safeguard the Olympic site.
No final decision has been made about this potential deployment but it does form part of Olympic Guardian, a major exercise in which security preparations are being tested this week.
Last night, the Ministry of Defence (MoD) confirmed the missiles would be deployed within the next few days. They describe them as ‘a useful deterrent’.
Defence Secretary Philip Hammond said: '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.
'The majority of this exercise will be played out in full view of the public and I hope that 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.'
Resident Brian Whelan, a journalist, said the MoD leaflet says the missiles will be fired only as a last resort.
He said: ‘They are going to have a test run next week, putting high-velocity missiles on the roof just above our apartment. They’re stationing police and military in the tower of the building for two months.
‘It’s a private, gated community with an old watch tower which is now a lift shaft.
‘We have an MoD leaflet saying the building is the only suitable place in the area. It says there will be ten officers plus police present 24/7. I’m not sure if they are going to live in the building. We have a gym and a pool and people have seen them there so it makes you think it will be some sort of Army base – it’s not ideal.
‘The property management company which runs the place put up posters and gave out the leaflets today.
‘The general tone was, “Great news, aren’t we lucky”, but that’s not normal, it’s not something people should have put on them.
‘I’ve looked these up [the missiles] and I don’t think they’re the kind of thing you can fire over a highly populated area like Tower Hamlets, think of the debris.’
Mr Whelan said the leaflet poses a series of questions residents might ask, such as: ‘Will this make me a target for terrorists?’
The 28-year-old said: ‘But the answer on it is that we will be safer with it here
‘From the few people I’ve spoken to, and the security we have here, they’re not happy about it. I don’t think it needs to be here at all.’
There are no plans to have soldiers patrolling the streets during the Games but marines will be working as part of the operation on the Thames and in Dorset.
The overall 23,700-strong security force for the Games includes a mix of military, private security guards and at least 3,000 unpaid London 2012 volunteers who will be used at the start of the security process.
It includes a 13,500-strong military force, which is more than the 10,000 that were deployed to Afghanistan, who will guard the Games.
There will be 7,500 military who are set to be deployed inside venues to do screening and search tasks, largely in the vehicle search areas.
