Britain's struggle to contain Muslim extremism points up a chilling trend across Europe: the rise of radical Islam, and with it, a willingness among a small but dangerous minority of young people to answer the call to jihad.

From the squalid suburbs north of Paris to the gritty streets of Sarajevo, young disaffected Muslims are increasingly receptive to hard-liners looking to recruit foot soldiers for holy war, European counterterrorism officials and religious leaders warn.

The continent, they caution, remains vulnerable to attacks by homegrown militants despite the heightened security and attempts at inter-religious dialogue that followed the deadly 2004 train bombings in Madrid and last year's suicide attacks in London.

"Their numbers are still relatively small, but I fear they could become larger as more young Muslims embrace militancy," said Fawaz Gerges, a professor of Islamic studies at Sarah Lawrence College in New York.

Gerges calls it "the jihad generation": converts to extremism in Britain, France, Germany, the Netherlands, Scandinavia and elsewhere who are becoming radicalized — partly in response to the conflicts in Afghanistan and the Middle East — and are spawning "self-generating" networks and cells.

"They're not part of Al Qaeda, but in their own eyes, they are foot soldiers" who share Usama bin Laden's ideology, he said.

Little is known of what may have motivated the 23 suspects in British police custody to allegedly plot to blow up U.S.-bound jetliners with liquid explosives. But many in their middle and working class neighborhoods said the communities have become alienated by U.S. and British policy in the Middle East.

"Governments in Europe insist this is a problem of ideology, but the real cause of this phenomenon is the political crisis that is sweeping the world with the war in Iraq and the situation in Palestine," said Azzam Tamimi, director of the London-based Institute of Islamic Political Thought.

Like the Sept. 11 terror attacks, the London bombings on July 7, 2005, "should have been lessons for everybody — that government policies endanger the security of everyone," Tamimi said. "The root cause has never been addressed. Unless they open a debate, the threat will never go away."

Recruiters for hard-line Islamist groups can turn some Muslim youths with little interest in religion into extremists in a matter of weeks, contends Pierre de Bousquet de Florian, head of France's counterterrorism agency.

An estimated 5,000 French Muslims embrace extremist Islam, according to a 2005 police intelligence report. France is home to about 5 million Muslims, the largest Islamic community in western Europe, and French authorities claimed to dismantle several cells earlier this year.

"Young people who are indifferent to religion fall in a matter of weeks into the toughest kind of Islam and, almost without any transition, into the most worrisome kind of activism," Bousquet de Florian told the newspaper Le Parisien last month.

But the rise of homegrown extremists — many of whom operate in small, close-knit circles difficult for law enforcement to penetrate — has complicated counterterrorism efforts in many countries.

The Netherlands has been on high alert since a Dutch Muslim of Moroccan descent murdered filmmaker Theo van Gogh in 2004. Spanish authorities have been monitoring some 250 suspected Islamic radicals, and in Bosnia five men are on trial for allegedly plotting an attack on an unidentified European country — significantly, one with troops in Iraq and Afghanistan.

An open letter published this weekend by prominent British Islamic groups said the "debacle in Iraq" and the failure to quickly secure a cease-fire in southern Lebanon as Israel waged a military campaign against Hezbollah militants has made Britain a target.

Britain's archbishop of York, the Most Rev. John Sentamu, said he thinks disenfranchised young Muslims turn to extremism not because of Islam but "because they are alienated, because they have been given a vision which is so imaginatively wicked."