Radical Islam is moving out of fundamentalist mosques and into your child’s bedroom, and the government doesn’t know how to deal with it.

This was the driving message behind a Senate Homeland Security and Government Affairs Committee report released Thursday addressing the spread of violent jihadist ideology online.

“We need a well-coordinated national plan to counter terrorist use of the Internet,” Chairman Joseph I. Lieberman, I-Conn, said at a news conference on the report’s release. Ranking Republican Susan Collins of Maine echoed his remarks.

“The United States lacks a cohesive and comprehensive outreach and communications strategy,” Collins said.

Written jointly by the committee’s majority and minority staffs, the report found that radicalization-by-Internet was a real and growing phenomenon in America as well as overseas. Those interested in, or susceptible to, terrorist propaganda can find immense caches of it online, the report said: radical Islamists use multimedia formats to exhort the use of violence, provide operational instructions, and raise funds and recruits.

Some online content is produced by organized groups, other materials by self-starting entrepreneurs who may have been influenced by virtual extremism.

But while the borderless, “information-wants-to-be-free” world of cyberspace has been a boon to the hunted al Qaeda, the hydra-like nature of online sites has confounded traditional law enforcement methods.

Efforts to shut down the Web sites have been the cyberspace equivalent of the “whack-a-mole” game, in which one platform is closed down only to have another spring up in its place, Lieberman said.

This problem has allowed Islamic extremists to bypass America’s physical borders and undermine cultural barriers that have served as a bulwark against extremism, the report noted. And while radicalization is less likely to occur here than in other Western countries, surveys have shown that a percentage of American Muslims agree with some extremist beliefs.

A Pew Research Center survey last year, for example, found that the diverse, immigrant community of Muslims in the United States is “assimilated, happy with their lives, and moderate with respect to many of the issues that have divided Muslims and Westerners around the world.”

However, 27 percent of those polled refused to express an opinion of al Qaeda; 5 percent had a favorable view of the terrorist group; and 8 percent said suicide bombings against civilian targets are often (1 percent) or sometimes (7 percent) justified in the defense of Islam.

The small percentage of Muslims who feel alienated from the mainstream are the most vulnerable to Islamist talking points, the report said.

It quoted February testimony from Director of National Intelligence Mike McConnell to the Senate Intelligence Committee.

“Over the next year, attacks by ‘homegrown’ extremists inspired by militant Islamic ideology but without operational direction from al-Qa’ida will remain a threat to the United States or against U.S. interests overseas,” he said. “The spread of radical Salafi Internet sites that provide religious justification for attacks, increasingly aggressive and violent anti-Western rhetoric and actions by local groups, and the growing number of radical self-generating cells in Western countries that identify with violent Salafi objectives, all suggest growth of a radical and violent segment among the West’s Muslim populations.”

Disruptions of terrorism plots at Fort Dix, N.J, in May and New York’s John F. Kennedy Airport in June suggest a rising threat that may be linked to the spread of violent jihadist propaganda over the Web, the report found.

Lieberman said moderate Muslims, with their largely positive experience of America, would provide the “best answer” in combating radicalization, and thus should be a focus of U.S. outreach efforts.

“It’s a battle, ultimately, for hearts and minds,” he said.

Reflecting the need for a better outreach effort, he quoted Defense Secretary Robert M. Gates, who bluntly observed last fall, “We are miserable at communicating to the rest of the world what we are about as a society and a culture, about freedom and democracy, about our policies and our goals. It is just plain embarrassing that al Qaeda is better at communicating its message on the Internet than America.”

The committee report posed a number of questions related to the issue: What legislation, resources, and tactics might be needed to fight the spread of Islamic extremism in the United States, what shape should a communications strategy take, and what roles should government, community and religious leaders play?

The committee would pursue answers in coming months, the senators said. Absent from the discussion, however, was mention of legislation (HR 1955) to create a national commission on radicalization and homegrown terrorism, which the House passed in October, 404-6. Collins sponsored a companion bill (S 1959) in the Senate, but it has not moved out of committee. The House bill, sponsored by Jane Harman, D-Calif., faced opposition from civil liberties groups over its definition of radicalization, which they said could infringe upon constitutional rights of free speech and beliefs.

Asked how much domestic radicalization is taking place through the Internet, the senators said there was some, but measurements were hard to come by.

“We don’t really know how many people are being radicalized because it’s very difficult to track with the Internet, the reach is unlimited, and that is alarming,” Collins said.

If there were any doubts al Qaeda and its ilk had slipped their brick-and-mortar bounds, committee staff displayed some of their virtual messaging.

On a monitor to the senators’ right flashed images of orange-suited hostages, angry hooded extremists, exploding roadside bombs, and digital depictions of rockets obliterating the United States — all in the name of Islam.

Matt Korade can be reached at mkorade@cq.com.