Editor's note: Raffaello Pantucci is an Associate Fellow at the International Center for the Study of Radicalisation (ICSR) at King's College, London, and the author of the forthcoming "We Love Death As You Love Life: Britain's Suburban Mujahedeen" (Hurst/Columbia University Press). His work can be found at http://www.raffaellopantucci.com.
By Raffaello Pantucci, Special to CNN
Just one day after the 2012 Olympics were awarded to London back in 2005, the British were given a graphic and deadly display of the domestic terrorist threat that British security services faced.
On July 7, 2005, four British-born suicide bombers sent by al Qaeda blew themselves up on the London transport system. Seven years on, the threat picture to the Olympics is one of uncertainty that will keep security services alert for the duration of the Games and beyond. A high-profile opportunity like the Olympic Games might seem too good for a terrorist to miss.
Since the bombing in Bulgaria of a busload of Israeli tourists, concerns have been ramped up about the possible threat to the Israeli Olympic team and, by extension, the Games.
Closer to home, the possibility of a Northern Ireland-related attack cannot be discounted. Revitalized dissident groups have long sought to strike against the mainland (and carried out 26 attacks in Northern Ireland last year.
But because of the 2005 attacks, the threat posed by Islamist terrorists has been the priority.
Whether these attacks would come in the form of an organized network or a lone attacker poses a further set of risks for Olympic security. Networks pose the threat of complex targeted incidents that cause chaos and mass murder. But as we saw with Anders Behring Breivik in Norway almost exactly a year ago, a lone actor can cause more chaos than a terrorist cell (at 77, Breivik's grim body count is higher than the July 7 bombers).
And as was evident in Aurora, Colorado, shooting last week, individuals don't necessarily need twisted political motives to carry out attacks - though Britain's tough gun laws make an attack like the Colorado incident unlikely.
In the runup to the Olympics, a number of arrests have highlighted how gravely Britain's security services regard the terror threat from homegrown violent Islamist networks. And while the threat from groups based in Pakistan may not be on the scale it was before, al Qaeda affiliates in Somalia, Yemen and increasingly North Africa alarm British services.
A routine traffic stop in the West Midlands on June 30 led police to a cell from Birmingham that had allegedly been planning to attack a march by the far-right English Defence League (EDL). This was rapidly followed by the unconnected arrest of a group of individuals in East London, some of whom were known to be active in public radical groups in the UK, and led to a series of charges for traveling to Pakistan for training and of helping and advising others to do the same.
In both of those cases, most police statements were prefaced by the comments that these incidents were "not Olympic related." And in neither case has any evidence been produced suggesting the Games were a target. In fact, from what evidence has been made public, it instead seems some sort of clash between rival communities is developing in the UK.
In the Birmingham incident, the cell reportedly was planning an attack against the EDL. The East London group allegedly had discussed, among other targets, aiming at the Wooton Basset, a city famous for its regular parades honoring British war dead. Previous clashes between locals and extremist Islamists who attend soldier's parades in the city and chant slogans about British soldiers being "butchers."
Protests such as these were much of the rationale for starting the EDL, and it now seems as though Islamists have decided to try to strike back.
The danger extends further to other communities. In Manchester last week, a jury found a married couple guilty of radicalizing online and plotting to attack the local Jewish community. Mohammed and Shasta Khan appear to have met on a Muslim dating site online. Using a home-based hairdressing business to obtain hydrogen peroxide, the couple planned to build a bomb while scouting out local Jewish targets. Their plan was disrupted after police investigated a family dispute, but their self-starting "lone wolf" jihad posed a dark prospect for Britain's security services.
London's Olympic security faces a wide array of possible terrorist threats, both from home and abroad. But the longer-term threat of home-grown factional or freelance violence is something that needs to be borne in mind. The Olympics are no doubt a large security concern, but Britain's security services need to be sure to keep their eyes on the longer term, too.