LONDON (AP) -- Britain has planned for a dizzying array of security nightmares surrounding the Olympics, including a coordinated attack like the London transit bombings, a dirty bomb or a cyberattack.
In the wake of France's deadly shootings, one scenario weighing heavily on the minds of security officials is the self-starter operating with little or no help from others.
And, they admit, there are limits to what security personnel can do.
"You cannot exclude something similar," said Denis Oswald, head of the International Olympic Committee's coordination commission for the London Games.
"Every Olympic venue will be specially protected, but of course, when you are in the street, people waiting for the bus waiting to go to an Olympic venue could be a target."
Mohamed Merah - a 23-year-old Muslim extremist who says he trained in Afghanistan - claimed responsibility for killing paratroopers, Jewish children and a rabbi in a weeklong shooting rampage in the French city of Toulouse. Police shot him dead last week after a 32-hour standoff.
French politicians have painted him as a "lone wolf" killer. But police are looking for possible accomplices, and suspicions grew that he had help when it turned out an apparent video of the attacks sent to the Al-Jazeera news network was not sent by Merah.
French officials say Merah moved in extremist Muslim circles in France and had been to Afghanistan twice. He told police he had trained in the Pakistani militant stronghold of Waziristan. He also had a long criminal record and a brother who had been suspected in a 2007 network that sent militant fighters to Iraq.
But French officials say there wasn't enough evidence of a threat to put Mohamed Merah under regular surveillance. Olympic security officials face a similar problem with some Islamic radicals in Britain ahead of the games.
"The reality is that there are hosts of people like this and most of them will never do anything," said a British government official who spoke on condition of anonymity to the AP because of the sensitivity of his work. "You can't follow everyone around."
That doesn't mean Britain isn't one of the most high-security nations in the Western world.
Since British suicide bombers killed 52 people during rush-hour attacks on July 7, 2005, MI5 and police counterterrorism units have vastly boosted their intelligence network. The country's surveillance agency, known as GCHQ, has the capability to listen in on people's telephone conversations and monitor their online communications. Surveillance units have also been attached to troops serving in places such as Afghanistan, specifically to gather intelligence that may lead back to Britain.
There are also special teams to look at suspect financial transactions - an aspect of anti-terror strategy that gained more attention following last year's terror attacks in Norway.
Rightist extremist Anders Behring Breivik's set off a 2,100-pound (950-kilogram) fertilizer bomb in the heart of Oslo that killed eight people before going on a shooting rampage at youth camp that left 69 dead. Breivik's name came up on a list of people who had transferred money to Polish chemical firm under scrutiny in an international anti-terror initiative - but Norwegian authorities didn't investigate further because his order was so small.
"The profile of these loners is different to what we saw with the four suicide bombers in 2005," said Noman Benotman, a former jihadist with links to al-Qaida who still maintains contacts within the jihadist community. "Many of them have some training, a strong conviction and they manage to stay off the radar for the most part."
Although the 8,000-mile torch relay starts in May - more than two months ahead of the games - security and law enforcement officials are bracing for a number of potential threats as the torch snakes though Northern Ireland, the Republic of Ireland and parts of the U.K.
Inside Britain's domestic spy agency of MI5, a clock counts down the minutes before the torch arrives in England.
"To terrorists, the Olympics present a golden opportunity because they know they will get the world's attention," said Benotman, who now works as an analyst for the London-based Quilliam Foundation. "It doesn't really matter whether they kill seven or 70."
Although there is no intelligence to suggest a credible and specific threat to the games, officials have spent years taking precautions for the Olympics since London won the bid the day before the 2005 attacks.
Britain is already known as a leader in 'Big Brother' surveillance - there are nearly 30 CCTV cameras near George Orwell's house alone in North London. The author of "1984" warned more than six decades ago of a time when it would be nearly impossible to escape from the watchful eyes of the state.
For the games, more cameras will be added to Britain's 4.3 million, and some will be used in conjunction with advanced facial recognition software and databases that can match vehicle registration numbers to names.
Olympic venues have also been designed with security threats in mind - special shatterproof glass has been installed, structures have been built with advice from explosives experts and pathways have been laden with curves and gaps deliberately meant to slow down a potential attacker.
"If you look at the Internet, there are web sites calling exactly for these types of lone-wolf attacks," said Rob Wainwright, head of The Hague-based Europol, which will be sharing databases with law enforcement officials during the Olympics.