The threat of domestic Islamic terrorism is a political issue wielded by political candidates and debated hotly in Congress. But how serious is the threat?
A documentary premiering on HBO Monday night, "Homegrown: The Counter-Terror Dilemma" by Greg Barker, and a related book, Peter Bergen's "United States of Jihad," seek to answer that question. The film's release comes as presidential candidates, particularly those in the Republican field, are warning of the problem.
"They have a sophisticated network of radicalizing people here in the homeland and around the world," Sen. Marco Rubio of Florida said at the Republican debate in New Hampshire on Feb. 6, about the Islamic State, or ISIS. Later on, he added, " We face a very significant threat of homegrown violent extremism."
The House Homeland Security Committee releases a monthly Terror Threat Snapshot , complete with an interactive map of the United States and has identified, as of its most recent report, 139 "terrorist cases involving homegrown Islamist terrorists since 9/11."
Barker, also the director of HBO's "Manhunt: The Search for Bin Laden," said he went into making the film "with a very open mind." Specifically, he wanted to answer the questions, "What is the real threat? What is the real motivation? How does the threat match the response?"
His film traces the response to the threat of domestic Islamic terrorism in the post 9/11 era, and leans heavily on the knowledge and expertise of the United States' most experienced counter-terrorism officials, as well as the people who are the targets of counter-terrorism actions.
What he found does not match up with politicians' portrayals. "There's a mismatch in what people conclude and what they say because of the perception of what the threat is," Barker said. "That's not to say there's not a threat. But in general ... many people who study it say the level of [threat perception] doesn't match the reality."
According to a recent Pew Research Center survey , "many Americans think a substantial segment of the U.S. Muslim population is anti-American." The poll found that "roughly half of the public believes that at least 'some' U.S. Muslims are anti-American,' including 11 percent who say 'most' or 'almost all' U.S. Muslims are anti-American and 14 percent who think 'about half' the U.S. Muslim population is anti-American."
The Pew poll of 2,009 adults was conducted by telephone Jan. 7-14 and has a 2.5-point error margin.
"The reason it's an issue on the campaign trail is that it's on people's minds," Barker said.
Republican presidential candidate Donald Trump, for instance, has called for the surveillance of U.S. mosques and has been unapologetic about voicing such concerns.
"I talked about Muslims. We have a problem. Nobody else wanted to mention the problem, I brought it up. I took a lot of heat," Trump said at the Feb. 6 debate in New Hampshire.
Barker added, "I think this is something that is just not going to go away, so we need to understand it and ask uncomfortable questions. 'What kind of society do we want here?' I try to give it a lot of space."
Not all the GOP presidential candidates have echoed Trump's calls for hard measures. New Jersey Gov. Chris Christie took a more nuanced position at the debate.
"I’m the only one up here who’s had a law enforcement background as a U.S. Attorney after September 11th. I went to mosques throughout my state to build bridges," Christie said, adding that his experience as governor and his state's Muslim population showed him, "These are good, law abiding, hard working people. What they need is our cooperation, and our understanding. They do not just need broadsides against them because of the religious faith they practice."
Barker sees "Homegrown" is a sort of natural follow-up to "Manhunt," his Bin Laden documentary that won a 2013 Emmy. It's also the second movie he's made based on a Bergen book. Bergen also wrote "Manhunt: The Ten-Year Search for Bin Laden -- from 9/11 to Abbottabad."
The work on "Homegrown" began right after the Boston Marathon bombings. Domestic attacks in the intervening years, such as last November's in San Bernardino, Calif., put an emphasis on the contemporary nature of the topic.
"We wanted to get the film out. It's very timely," Barker said.