A Royal Air Force Puma helicopter flies over the 2012 Olympic Stadium during a training flight over London on Aug. 18, 2011. / AP
(CBS/AP) Hundreds of American intelligence, security and law enforcement officials are flying across the Atlantic these days in the biggest U.S.-U.K. security operation on British soil since World War II.
Some Americans will even be embedded with their British counterparts during the Olympic Games , sharing critical intelligence and troubleshooting potential risks. Dozens of Interpol officers will also be deployed.
The unusual collaboration is rooted in common threats the partners have faced since the Sept. 11 terror attacks on the U.S. and Britain's own deadly suicide bombings in 2005.
Britain was America's closest ally in Afghanistan and Iraq, making it a prime target of Islamic terror groups. And dozens of recent terror plots, including the 2006 plot to blow up nearly a dozen trans-Atlantic airliners, have been hatched within Britain's sizeable Muslim population, more than 1 million of whom have ties to Pakistan.
Although other Olympics have taken place since 9/11 - Salt Lake City, Athens, Turin, Beijing and Vancouver - London poses a different breed of security challenge.
"I'm confident that there is more than adequate security here for these games," Louis Susman, the U.S. Ambassador to the U.K., told The Associated Press. "That said, we live in a tumultuous world, whether that be in New York or London."
Intelligence officials say there has been an expected increase in chatter among extremist groups but there are still no specific or credible threats to the London games. The terror level is labeled substantial, a notch below severe and what it has been for much of the past decade. A substantial threat level indicates that an attack is a strong possibility.
The potential threats to the London games are broad and diverse: a lone wolf attacker such as Norway's Anders Behring Breivik who confessed to killing 77 people; a possible non-Asian Muslim convert who could slip by security with a European passport; a coordinated strike like the Sept. 11 terror attacks or a debilitating cyber-attack.
Although al-Qaida has been weakened by targeted U.S. strikes, its affiliates in places like Somalia and Yemen have stepped up their activity and increased their capabilities. They've even been working on bombs that can go undetected in airport scans.
The overall security numbers are staggering. The Games will be protected by some 12,000 police officers during peak times and 23,700 security staff, a number that includes some 13,500 troops on standby, which is more than the 9,500 British troops currently in Afghanistan.
Here are some of the security procedures being planned: