Tourists stand under Union Jack umbrellas as they snap photos of the Olympic Rings on London's Tower Bridge: A recent arrest has the British city's security on high alert.

REUTERS/Andrew Winning

ritish authorities have detained an alleged al Qaeda militant who managed to travel through London's Olympic Park five times, despite a court order that he stay away. Should the incident alarm spectators and athletes who will be at the facility when the Summer Games start on July 27? Here, a brief guide:

Who is the suspect?
Authorities have identified him only as "CF," a 24-year-old Briton of Somali origin who, according to intelligence agents, once tried to get to Afghanistan to be trained as a terrorist and, possibly, a suicide bomber. He is also suspected of having fought for the Somali Islamist group al Shabaab, and trying to recruit Britons to the group's cause. He is one of nine suspects whose movements and computer use have been limited under the U.K.'s Terrorism Prevention and Investigation Measures.

What is he accused of doing?
CF is being prosecuted for violating an order from Britain's Home Office to stay away from Olympic Park. He allegedly passed near the main Olympics venue in a train five times. Counter-terrorism officials were able to track his movements at all times because he has to wear an electronic tag fitted with a GPS device. While his lawyers say he was just trying get to their office — a trip they believed wouldn't violate the restrictions imposed on him — security officials are worried that he might have been conducting reconnaissance for an al Qaeda cell planning an attack during the games.

How tight will security be during the games?
The London Olympics will boast the most extensive peacetime security operation the U.K. has ever seen. The military is mobilizing 13,000 soldiers — more than the country has in Afghanistan. It's also mooring its biggest warship in the Thames, patrolling the skies with Typhoon fighter jets, and putting helicopters with airborne snipers on board to respond to emergencies. Another 20,000 civilian security guards have been hired to help reinforced local police units. "All of these things say to sophisticated terrorists: London is expecting you," Patrick Mercer, a member of Parliament, tells The Daily Beast. "Don't try it."

Does that mean everyone can breathe easy?
"This doesn't exactly inspire confidence," says Sam Leith at the London Evening Standard. If 130,000 police officers and the 3,800 employees at the MI5 intelligence service couldn't keep a guy wearing an ankle bracelet with a tracking device away from Olympic Park, how are they going keep an armed and suicidal terrorist who isn't even on their radar screen from striking? Well, "security around the Olympic stadium in London is really very, very good, so an attack there is highly unlikely," Valentina Soria, a counter-terrorism analyst at the Royal United Services Institute, tells The Straits Times. The more immediate danger is that a "lone wolf" terrorist will strike at a shopping center or other soft target elsewhere in London, outside the reach of Olympics security.

Sources: Daily Beast, London Evening Standard, New York Daily News, Straits Times, Telegraph