Assistant Chief Constable Marcus Beale urged anyone who knew of people being "radicalised" to come forward.
The second is security, and specifically the fear of where a radicalised French Islam might lead.
Yet Burundi's Hutus were radicalised by the overthrow of their democratically elected government.
In a report issued on Monday, a UN-appointed inquiry team said the conflict had become "increasingly sectarian... radicalised and militarised", according to AFP news agency.
Jonathan Evans, the head of MI5, Britain's domestic intelligence service, is among those who worry that the war in Gaza will have radicalised more Muslims.
The news agency reported earlier this week that her older son, Tamerlan, had also been added to the list, after Russian officials warned the US authorities he may have become radicalised.
But he faces the same underlying problem that defeated his predecessor: how to stimulate investment and restore order to the public finances in the face of the demands of radicalised social groups.
He said he did not believe that Mr Abdulmutallab had been acting alone, adding that police and security services were examining whether he had been radicalised while at University College London (UCL).
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The event will look at ways of dealing with piracy off the coast of Somalia, protecting ships in the Gulf of Aden, challenging extremist groups in Somalia and the risk of UK citizens being radicalised there.
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Of the four main threats, it is the lone individual, self-radicalised on the internet and with no suspicious contacts or record of activism, who is the hardest to identify and deal with: organised networks are vulnerable to penetration.
Small businesspeople who were formerly the base of Pasok but who have been radicalised by the tax rises, tax clampdowns and repeated heavy policing of demonstrations, and who are the most likely to be ruined by any long-term structural reform in Greece.
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