The recent terror attempts in London and Glasgow serve as a reminder that radicalized Muslims could be living anonymously in our communities and planning the next Sept. 11-grade attack. But the homegrown terrorist problem in the United Kingdom is far more extensive and severe than the problem in the United States, experts say.

Despite the fact that the United States remains the No. 1 target for al Qaeda, the jihadist movement has been penetrating Western Europe for decades whereas it has just started picking up speed in this country in the past 15 years, said Walid Phares, a senior fellow at the Foundation for Defense of Democracies, a nonpartisan think tank dedicated to fighting the ideologies that support terrorism.

Muslims who immigrated to the U.K. are generally from South Asian nations such as Pakistan, where the most radical forms of Islam are practiced and taught, said Akram Elias, president of the Capital Communications Group, an international consulting firm based in Washington, D.C.

In contrast, he said, most U.S. Muslims emigrated from Middle Eastern regions such as Yemen, Lebanon and East Asia, where there isn’t as high a concentration of this radical form of Islam, known as Wahibism.

In addition to having radical roots, Muslim communities in the United Kingdom are more disenfranchised and less integrated than in the United States, and this lays an even greater foundation to foster radicalization.

The United States historically has assimilated immigrants into society much better than the U.K., said Brian Michael Jenkins, a counterterrorism expert with Rand Corp. “We’re a nation of immigrants,” he said. “Accented English is not a barrier to social, economic or even political advancement.”

Al Qaeda has been building a major terrorist network in the U.K. for years, Jenkins said, and that just hasn’t been the case yet in America. “There is recruiting that goes on in this country, but not on the scale or intensity in the U.K.,” he said.

But experts warn that could change in the future.

“What we see now happening in Europe and in Britain is our future if we do not do well in the war on terror here at home,” said Phares, of the Foundation for Defense of Democracies. He added that it is critical to stop the radicalization at the initial stages and not at the end stage when an attack is about to become operational, as happened last week in the U.K.

“Overall, we’ve taken the threat more seriously than the U.K.,” said Bruce Hoffman, a counterterrorism expert at Georgetown University. In the immediate aftermath of the Sept. 11 terrorist attacks, the United States made “positive and assuring overtures” to the Muslim American community, he said, and this paid off in dividends.

For instance, in the New York City region, members of the Muslim communities reached out to the Department of Homeland Security after the 2005 London subway bombings. While the Muslim communities in America are more assimilated than those in the U.K., Muslim leaders in the New York area wanted to ensure that members of their community would not become similarly disenfranchised and prone to radicalization, said Marty Ficke, the former special agent in charge of U.S. Immigration and Customs Enforcement in New York City. A series of forums and discussion groups ensued, fostering much-needed dialogs between members of the Muslim communities — particularly the youth — and law enforcement. The way to combat radicalization is to go out into the community and open up this type of communication Ficke said.

Jenkins, of Rand Corp., said America’s biggest problem is going to be the emergence of small groups hatching up lethal conspiracies. “Any damn fool can make a bomb and kill a lot of people,” he said.

Hoffman also warned about dismissing homegrown organizations as amateurish and lacking direct ties to al Qaeda. “The amateurs can kill just as efficiently as professionals,” Hoffman said. When one plot is foiled, there’s likely another already in the works, he said, and the United States is certainly not immune to increased radicalization.

Eileen Sullivan can be reached at esullivan@cq.com.