Yet they were able, with limited training, to cause havoc in central London on 7 July, killing some 56 people and injuring 700 others. The subsequent bombing wave, on 21 July, failed only because the explosive charges did not detonate -- another sign that the young men involved were amateurs at storing or handling explosives.
One of the most chilling aspects of the bombings is exactly this, that the first suicide bombers seen in Western Europe were at one time law-abiding citizens who were radicalized and indoctrinated quickly and so secretly that even their own families apparently did not know about it.
Paris-based security analyst Walter Posch of the European Union Institute for Security Studies, said that terror organizations like Al-Qaeda are not recruiting the "obvious" radical Muslims -- those who speak out, or attend mosques that are known to be hard-line.
"The radical scene by and large is [already] quite heavily under surveillance in any European country, but what you cannot watch is the ordinary operative who is below the radar screens of surveillance," Posch said.
Posch added that studies show Al-Qaeda recruits come from circles of apparently normal, law-abiding citizens who do not arouse attention through radical Islamic stances, and who therefore are much harder to detect.
Another analyst, Amsterdam public-opinion surveyor Maurice de Hond, said modern technology helps sustain these largely isolated secret radicals by allowing them to enter a large community that supports their idea of self-destruction for a cause.
De Hond said that in this sense there is a common link between the London bombings and the case of Mohammed Bouyeri, who today was sentenced to life in prison for killing Dutch filmmaker Theo van Gogh, who had made a film strongly critical of the treatment of some women under Islam.
"In a way there is a connection between what happened to Van Gogh and the things that are now happening in London, and that's because of the virtual world of the Internet," de Hond said. "Everyone who wants to be, is part of a bigger group, of that virtual group. We don't think that Mohammed [Bouyeri] is really part of Al-Qaeda, or that he has an assignment from [Al-Qaeda leader Osama] bin Laden, but being a part of that bigger world on the Internet, in a way, they feel they are personally part of that group."
So what can be done to tackle the growth of homegrown radicalism in Europe? So far, in light of the London bombings, European countries are coming to realize more clearly that the threat stems not only from foreign terrorists, but also from internal sources influenced by complicated social factors.
Imam Ibrahim Mogra, chairman of the Community and Mosque Committee at the Muslim Council of Britain, outlined the obvious moves that need to be made.
"We need to make sure that we regulate the kind of people who come and talk to our congregation," Mogra said. "If there is any guest speaker, we have to make sure that they know that they cannot preach any hatred. We need to make sure that people do not abuse the surroundings outside the mosque to distribute or to preach hatred. And we need to make sure that we inform the authorities if anyone is doing something that is not conducive to peaceful coexistence."
In Paris, French Interior Minister Nicolas Sarkozy said yesterday that France will not tolerate any kind of activity provoking hatred or violence, including anti-Semitism.
Sarkozy defended the deportation of an Algerian imam, Abdelhamid Aissaoui, who had been convicted in 1999 for playing a role in an attempted attack on a high-speed train. Sarkozy made clear that expulsion of similar radicals would be done without hesitation.
Such actions may reduce the "loud" radical elements from society, but will do little to neutralize the "silent" radicals such as the London bombers. Analyst Posch said a deeper perspective is needed for that.
Social maladjustments create conditions which can nurture the growth of radicalism. For instance, the 7 July London bombers were British-born but from an immigrant demographic seen as having few prospects for advancement. The large Turkish minority in Germany is still not integrated into mainstream society. And in France, many Muslim youths likewise feel left on the fringes.
Posch said also that Muslims may have been in Europe for three generations, and have lost the original context of their Muslim faith, creating tensions between generations. That's why it is important for young Muslims to receive religious teaching appropriate to their situation as members of communities that are slowly finding their way forward in an alien environment:
"Teachers and structures coming from abroad do not have the sensibilities and understanding of the needs both culturally and politically of the Muslim societies in Europe," Posch said. "So one long-term aim must be that Muslim education in Europe should be in the hands of Muslims feeling European."
The delicate balancing act will be to work toward eradicating homegrown radicalism in Europe while preserving individual rights so that large sections of the Muslim populations around Europe do not feel persecuted on grounds of race or culture.