A Former FBI Agent on Whether Americans Should Worry About ISIS Attacks

With the release on Sunday of a video purporting to show nine of ten known Paris terrorist attackers training in Syria and Iraq, national security agencies across the world are likely doubling their efforts to identify ISIS sympathizers within their own borders. French Interior Minister Bernard Cazeneuve has already suggested terrorists planned to carry out another mass attack on the streets of Paris; at the same time, he defended his government's plan to extend the state of emergency imposed after the prior attacks.

Meanwhile, it looks increasingly plausible that foreign-trained ISIS fighters might eventually return home to attack the United States.

In the case of the ISIS Paris attackers, one alleged militant, fugitive Salah Abdeslam—whose brother Brahim Abdeslam blew himself up in a Paris café during the attacks—is not seen in the video and remains on the run, having reportedly fled for Belgium. It is likely that he not only fears capture by European intelligence agencies, but also retribution from ISIS for failing to carry out his mission by either getting killed or committing suicide during the attack. If the latter is true, Abdeslam would be a prime target for capture and debriefing, as he may fear his old friends more than he fears French authorities.

During a 28-year career with the FBI, where I worked both counterintelligence and counterterrorism, evidence of clandestine tradecraft—foreign-trained terrorists returning home to enmesh themselves in society—was rarely seen in domestic terrorism cases. Prior to the attacks by al Qaeda on 9/11, alleged foreign terrorists were not suspected of receiving extensive training in secret intelligence methods and underground cell dynamics.

The primary attribute required of an international terrorist was simply a willingness to die.

After the attack in San Bernardino by US citizen Syed Rizwan Farook and his Pakistani-born wife Tashfeen Malik, investigators from the police, the Department of Homeland Security, and FBI were initially concerned that the attacks were directed by ISIS from overseas. However, according to David Bowdich, the assistant director in charge of the FBI's Los Angeles office, the Bureau did not "…see any indication of a foreign-directed terrorist attack."

Still, this latest video serves as the surest indication yet that the Islamic State was responsible for both the planning and execution of the Paris tragedy. More importantly, it suggests that ISIS is actively training and sending clandestine cells of foreign fighters back home to engage in domestic terrorism. This development, while not entirely unexpected, ratchets the battle against Islamic State terrorists to another level—and has to send a shiver down the spine of all US law enforcement.

Since the death of Osama bin Laden, the primary international terrorism threat addressed by the FBI within the United States has been from homegrown ISIS aficionados who had not travelled to Syria or Iraq, but who were nonetheless inspired to the engage in terrorism by videos similar to the one released. This may be changing. Indeed, whether or not the FBI continues to pursue the possibility that Farook and Malik were acting on orders from ISIS, the existence of underground cells of ISIS foreign trained terrorists inside the homeland is the ultimate investigative nightmare for the United States.

Historically, the Bureau has been unsuccessful in infiltrating clandestine terror groups or in the development of informants within existing terror cells. The Weather Underground, Black Liberation Army, FALN, and the United Freedom Front existed freely and operated underground for years without any significant infiltration or impediment by the FBI. Similarly, closed cell criminal enterprises like the Mafia or violent street and prison gangs have long resisted the placement of undercover agents within their midst. One reason is a criminal enterprise's very strict vetting, up to and including participation in murders. (The cases of the penetration of the Bonnano and Lucchese crime families by FBI agents Joe Pistone—a.k.a. Donnie Brasco—and Jack Garcia are among the notable exceptions.) Deep long-term undercover work infiltrating terrorist groups is not something that most FBI agents or law enforcement aspire to do.

Check out the trailer for our upcoming HBO piece on the fight against ISIS.

The recruitment of informants and assets as "flies on the wall" sources of information have been much successful in targeting clandestine cells, whether criminal, terrorist, or hostile foreign-intelligence driven. These types of human intelligence, or HUMINT sources, often lead to much more productive electronic surveillance and wiretaps of clandestine cells. Retired Chicago FBI agent Bill Dyson is one of the few I personally knew who successfully employed the technique. But the identification, recruitment, and development of access by these types of informants is notoriously difficult. The hours are long and the rewards limited unless you get really lucky.

It is only a matter of time before the FBI is confronted with a video similar to this one, which targeted the British government specifically. When that day comes, will US officials stick their heads in the sand, like the British did earlier this week when a UK spokesman said, "We are currently examining this latest Daesh [ISIS] propaganda video—another desperate move from an appalling terrorist group that is clearly in decline"?

If and when Americans execute a Bataclan-style attack on their own country directed by ISIS terrorists abroad, my hope is that the FBI and local law enforcement will respond as they have in the past: with skill, professionalism, and a fair amount of good luck.

David Gomez is a retired FBI agent and former counterterrorism executive in Seattle, Washington. He is currently a Senior Fellow at George Washington University's Center for Cyber and Homeland Security. Follow him on Twitter.