As London prepares to host the Olympics later this month (July 27-Aug 12) the top concern for organizers is security. Since the attack at the Munich Games in 1972, and with the rise in terrorism in recent years, security takes up a large chunk of the Olympics' budget, and a large amount of attention for officials, fans and participants alike.
British officials are using all their resources to prepare for any contingency, including putting fighter jets on alert. They are also deploying 17,000 troops and installing anti-aircraft missiles in residential neighborhoods around the Olympic Park. Even the navy is getting involved, with a warship and small boats on duty on the River Thames.
The military role had to be increased by several thousand troops at the last minute, when a private contractor failed to recruit as many security guards as it had promised. Officials say the glitch won't affect the safety of the Games, but it does present challenges according to security consultant David Rubens.
"I think the honest answer is no, they're not ready," said Rubens. "And they're certainly going to have to make do and mend, rather than manage the situation as they had hoped to do from the beginning of the operation."
Most of the millions of Olympics fans and tens of thousands of participants won't see the military aspects of the security. For them, going to the Games will be like going through an airport. The security staff had a chance to practice during Olympic trial events earlier in the year, including of the smallest team members.
The Olympic Park security control room also got a work out, as officials practiced using the latest technology to monitor all corners of the 200-hectare area. The center brings together civilian and police officials, among them London's top police officer for Olympics security, Assistant Commissioner Chris Allison.
"You will see a high-profile policing presence outside," said Allison. "But the key for us is to do it in a way that's not oppressive, where the focus can be on the sport, the focus can be on the spectators."
It will be a challenge to secure dozens of Olympics venues all over London, and indeed throughout the country.
The Chairman of the London Olympics Organizing Committee, former British gold medalist Sebastian Coe, says there is "no appetite for risk," but security won't dominate the Games.
"We're inviting people to come to London to celebrate the greatest sporting event that this country has ever seen," Coe noted. "We're not inviting people to 'Siege City.' So there is a proportionality here. And in this country, we always pretty much get that right."
As the Games proceed, people all over the world will be watching to see whether the organizers succeed through the challenging 17 days of the Olympics.