Growing concern of a terrorist threat cultivated within the United States has led key House members to push legislation to create a commission to better understand the root causes of violent extremism.

An amendment to the Homegrown Terrorism Prevention Act (HR 1955) would create a national commission to study the origins of violent radicalization and homegrown terrorism. The provision could be offered as soon as next week during a markup of the bill, which has already garnered strong bipartisan support on the House Homeland Security Intelligence, Information Sharing and Terrorism Risk Assessment Subcommittee.

Chairwoman Jane Harman, D-Calif., will offer the amendment to the bill she introduced April 20 with ranking Republican Dave Reichert of Washington.

“I still don’t know what makes a homegrown terrorist,” Harman said at a Thursday subcommittee hearing. “I am worried. We must learn from the British experience and fix what needs fixing in this country.”

Harman alluded to 200 different terrorist plots that have surfaced in the United Kingdom involving roughly 1,600 British citizens and cited specific cases where American citizens have conspired to harm American civilians, critical infrastructure, and military facilities and personnel.

The examples she highlighted included: Timothy McVeigh, an American-born man who was the chief culprit in the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma City; Russell Defreitas, a Guyanese-born American who planned to detonate pipelines and fuel reserves at John F. Kennedy International Airport; several foreign-born legal residents of America who colluded to attack Fort Dix in New Jersey; and Adam Yahiye Gadahn, a 28 year-old American-born citizen who serves as the English-language spokesman for al Qaeda.

The amendment would establish a commission to study factors that motivate American citizens and residents to plan attacks and produce solutions that might counteract these influences.

Reichert cited radical elements in prisons, content on the Internet, and the influence of charismatic radicals as common factors leading to homegrown terrorism.

Panelists who testified at the subcommittee meeting recommended that the commission include: behavioral scientists, social network specialists, local police and international intelligence experts, liaisons to the Muslim-American community, constitutional lawyers and law enforcement with experience investigating organized crime.

“[Homegrown terrorism] is the principal threat that we face as a country and it will likely be the principal threat that we face for decades,” said Brian Jenkins, a Rand Corp. expert in terrorism, counterinsurgency, and homeland security. Unless a way of intervening in the radicalization process can be found, “we are condemned to stepping on cockroaches one at a time,” he added.

The commission’s work should produce new instruments for combating homegrown terrorism, which can complement the asymmetric approach that focuses on “killing and capturing” terrorists, added Frank Cilluffo, director of the Homeland Security Policy Institute at George Washington University.

Cilluffo said one of the primary objectives the commission should focus on is a more solid understanding of Islam as well as the narrative that radical groups promote pitting Western societies against Muslims. Gaining these perspectives would allow the United States a better opportunity to publicly deconstruct the campaigns promoted by radical groups like al Qaeda. Furthermore, the United States should adopt policies that match the words they use to promote its counter-narrative.

The commission should also look into methods for preventing Muslim-Americans from experiencing social alienation and stopping non-Muslim Americans from experiencing Islamophobia, said Salam Al Marayati, executive director of the Muslim Public Affairs Council. Both of these developments can make people vulnerable to messages promoted by violent radicals.

Another chief object the commission should undertake is to find ways to improve local police intelligence gathering and fostering a better relationship between police and communities.

Without doing something to drain the pool of people willing to take violently radical actions, homegrown terrorism will remain an ominous threat, the panelists agreed.

“Intent is the constant and capability is the variable,” Jenkins said. “There are bunches of guys across the country [with bad intentions].”

Matthew M. Johnson can be reached at mjohnson@cq.com.