The 1993 World Trade Center bombing, and the conspiracy trial of a blind Muslim cleric and 11 of his followers that is taking place in New York, have persuaded many Americans that a jihad, or holy war, is being waged on their soil by Islamic extremists. And in the new climate of hatred and fear, the overwhelmingly law-abiding and moderate Arab-American community is more fearful for its safety than at any time in recent memory.
To be an Arab-American or an observant Muslim in America is to live with the constant anxiety of being from one of America's most disliked ethnic and religious groups. Members of these communities are regularly stereotyped by Hollywood and the media as terrorists or fundamentalist fanatics, and their most innocent activities, such as attending the mosque, are open to misinterpretation. An Arab-American research firm recently found in an opinion poll that Muslims were the most disliked ethnic community in America. Parents tell of how their children are already called terrorists and killers at school and how schoolbooks invariably portray Arabs in a negative light.
Many Americans reserve a special animosity for Muslims, Arabs and Iranians since the humiliation of the embassy hostage-taking episode in Iran in 1979. With every subsequent terrorist outrage directed against American interests,, Arab-Americans - or "rag-heads" as they are derisively known - have borne the brunt of popular outrage.
Many Arab-Americans have been in the US for more than three generations; the largest concentration of those of Arab descent being in Detroit. Many Palestinians have settled in California and New York, where they have found themselves living cheek by jowl with Jewish Americans. Islam is also flourishing: mosques are sprouting up all over the country, and many moderate Muslims have become as politically active and assertive as their counterparts in the American-Jewish community.
But it is the activities of the extremist fringe of Arab-Americans and immigrant Muslim fanatics that are now absorbing the attention of the FBI and police. There is credible evidence that the US is now a fertile environment for fund-raising by militant Islamic groups. Much as the IRA used Irish-American sympathisers to raise money and guns before last year's ceasefire, Islamic fundamentalists are raising cash and producing propaganda videos extolling worldwide jihad. They are also alleged to have built up an underground political organisation dedicated to urban terrorism in America.
Cells of Islamic extremists are known to be in place across America, and the militants have developed an elaborate recruiting network in more than 38 American cities. A documentary broadcast on America's Public Broadcasting System (the equivalent of the BBC) last November showed video footage of Muslim clerics and leaders making blood-curdling speeches in American mosques and meeting rooms. The footage included an Islamic leader addressing a meeting in Oklahoma City in 1989 and went on to allege links between speakers at the meetings and the 12 being tried for plotting to bomb large parts of lower Manhattan and the United Nations.
Stephen Emerson, the journalist on the PBS documentary, traces the origin of the Islamic militant networks to the $3bn (£1.9bn) that the US spent backing mujahedin rebels in Afghanistan nearly 15 years ago. His programme identified a key figure as Abdullah Azzam and produced video footage of him preaching holy war to an Oklahoma City audience. At another meeting, in Brooklyn, described as one of the first jihad conferences, he said: "There is no turning back from the stone to the pistol to the Uzi to the cannon to the rocket-propelled grenade and then you can expect Allah's ultimate victory."
Mr Emerson is not without his critics in the US, however: he has been branded as biased and anti-Palestinian in the past. Vince Cannistraro, the former anti-terrorism chief of the CIA, said last night that it misses the point of terrorism to suggest that there was "a fundamentalist hiding under every Arab-American bed" and that "Emerson is wide of the mark."
The hunt for someone to blame for the outrage is at fever pitch, however, and there is a real danger that an entire community will be branded for the actions of a core of dedicated terrorists - as happened in Britain, where the Irish community bore the brunt of public and official anger for IRA bombings in Birmingham and elsewhere.