In the aftermath of the terrorist attacks in Paris, more than half the country's governors have declared that their states will be off-limits to Syrian refugees fleeing the civil war raging in their country. Those who oppose these restrictive state policies have based their arguments on legal or moral grounds. But there is another, pragmatic reason for allowing Syrian refugees into the United States: They present a unique intelligence opportunity to help prevent a Paris-style attack from occurring here at home.
One of the recommendations made by the 9/11 Commission following the Sept. 11 attacks called for the intelligence community to "ensur[e] a seamless relationship between human source collection and signals collection at the operational level." Translation: Information gleaned by human sources -- known in intelligence as HUMINT -- should keep pace and coordinate with information obtained from electronic, or SIGINT, sources. Ideally, one kind of intelligence should enhance and corroborate the other, leading to more detailed and accurate intelligence overall.
Since 2001, however, the United States has relied much more heavily on electronic rather than human sources, and the consequences are evident in the Paris attacks. Technological advances over the last 14 years allow the U.S. to access everything from any individual's entire phone call history to up to 1.7 billion emails a day. But what the Paris authorities most needed were people who lived in the suspects' Brussels community and could track their day-to-day movements and report in-person conversations. This is the kind of intelligence that no cellphone or email can provide.
Unfortunately, enlisting human informants can be difficult, especially abroad. The CIA has an uphill battle when developing human contacts in foreign countries, often working in hostile territory where approaching potential sources can lead to exposure. The CIA also doesn't have much to offer foreign sources apart from financial incentives -- unless an individual happens to have some personal affection for the U.S. or the West, they have no reason to put themselves in danger to help our government. With human sources so hard to come by, it's difficult to vet the true intentions of those who do get on board: One of the most promising CIA sources after 9/11, Humam al-Balawi, turned out to be a triple agent for al-Qaida who lured seven officers into a deadly explosion.
The Syrian refugees offer a rich pool to enhance our domestic human source capabilities, and have several advantages over contacts developed abroad. For one thing, the FBI -- the agency responsible for domestic intelligence -- already has established relationships within many immigrant communities. These existing relationships allow the FBI to more easily build and vet new ones with newly arrived populations, allowing us to create a wider intelligence "net" with which to gather information and uncover potential domestic plots. In addition, refugees, like the immigrant populations they are integrating into, have a personal reason to help the U.S. -- they are grateful to be here and have a vested interest in helping the country they now call home. During the 2003 invasion of Iraq, for example, thousands of Iraqis living in the United States provided valuable information that assisted intelligence and military on the ground in Iraq. Last, but most important, they can easily see, hear and speak with the people we most want to know about in the U.S., which is something that we can't replicate through mass data collection alone.
It's very unlikely that the next terrorist attack will be masterminded by a penniless family seeking a safe haven...from violence and terrorism. The odds are higher that any domestic attack will be propagated by a few individuals already living here, as was the case in Paris (none of the six currently-identified suspects was a Syrian national -- all were French or Belgian). To disrupt them, we need people living in their communities to be the eyes and ears for our domestic intelligence efforts. We should remember that America's diversity, and the gratitude people have for a country that welcomed them, are potentially our best assets in combating the terrorist threat at home.
A version of this article first appeared in The Hartford Courant on November 22, 2015.