LONDON, UK — Visitors flocking to the London Olympic Games next week are unlikely to have an old 15-story apartment building on their itineraries. Indeed, few people outside Waltham Forest, the down-at-heel district in which it stands, are aware of its existence.

But in East London, where most of the events will be held, the the Fred Wigg tower has become a battleground for campaigners who believe the government’s security measures are threatening the civil liberties and safety of ordinary Londoners.

That’s because the British defense ministry has made it the front line of a major military offensive against the games’ potential enemies by installing a battery of surface-to-air missiles on the building’s roof.

Critics warn such measures may help the London games come to be remembered for fear.

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Kieran O’Rourke, a lawyer who is helping the block’s residents launch a legal battle against the armaments stationed on their roof said the building was unknown until the ministry mentioned the deployment on its website.

“So Al Qaeda, the Real IRA or any terrorist group that likes to target British military personnel now know where they will be based for the next two months,” he said. “These are homes, and these people are going to feel very disrupted or at risk of a terrorist attack.”

The apartment tower is one of six sites in and around East London that may be used as a base for Rapier missiles, whose warheads can bring down a passenger jet. They will form part of a “ring of steel” protecting the 80,000-capacity Olympic stadium and other venues.

Defense secretary Philip Hammond, who admitted London has faced no known threat since suicide bombers killed 52 people in 2005, defended the measures as something the public expects during a “once-in-a-generation” event. “Ground-based air defense systems will form just one part of a comprehensive, multi-layered air security plan which, I believe, will provide both reassurance and a powerful deterrent.”

But activist Chris Nineham, of the group Stop The War, questioned the tactical value of basing missiles on the Fred Wigg building and in other locations. "We don't believe they will add anything to security,” he said. “If they are going to be used, they will explode over some of the most densely populated areas in London."

Britain’s military insists the missiles will be used only in the event of “specific orders from the highest levels of government in response to a confirmed and extreme security threat.” Mobile ground radar systems and observers with binoculars will identify the threats.

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Other security measures include the stationing of Typhoon fighter jets in northwest London along with sniper-bearing helicopters able to shoot down aircraft entering restricted airspace without permission.

The naval assault ship HMS Ocean will be positioned on the Thames River near Greenwich, another Olympic venue, to be a logistical support base. A second assault vessel, HMS Bulwark, will be stationed at Weymouth Bay in the south, where sailing events will be held.

River patrols will carry controversial sonic weapons. Although the defense ministry said the American-made long-range acoustic devices would be used primarily in “loud-hailer mode” for issuing warnings, it is capable of emitting painful sound waves.

And then there are the troops. Initial security plans envisaged 10,000 personnel. But mounting concerns during seven years of preparation have prompted increases to 23,700, including private contractors.

In the final days before the opening ceremony, it emerged that a private company that won a $750 million contract to supply security staff for the games failed to provide enough guards, forcing the government to draft in an additional 3,500 troops.

They will man 2,000 x-ray scanners and control bomb-sniffer dogs recalled from Afghanistan as security cameras peer down from every rooftop and street corner. A network of 30 control rooms will coordinate operations.

Civil liberties campaigners are concerned such comprehensive surveillance may cause unnecessary alarm or be used to erode fundamental freedoms, accusations they say could ruin London’s moment on the world stage.

The human rights group Liberty says mass surveillance and loss of liberties would be “completely contrary to the spirit of the Olympics. What a shameful legacy for London 2012 that would be.”

Sally Jane, an activist with the Occupy London movement, said the security measures sent a message of fear. “The Olympics are supposed to be about sporting achievement,” she said. “But it just seems to be an excuse to turn London into a militarized police state.”

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Back at the Fred Wigg tower, residents remain baffled by the decision to turn their home into a missile base. They have sought a court injunction to block the move they say violates their human rights.

“Of course the Olympics need police,” said Ali, a local who lives near the tower and declined to give his last name. “But rockets and missiles in the middle of a community are not good. Something goes wrong, boom!”