The shocking events that began with the Patriots Day bombings and ended with a hail of gunfire on Friday night in Watertown, Massachusetts may indeed mark a new phase in the United States' struggle with terrorism. If indeed the two suspects, brothers Tamerlan and Dzhokhar Tsarnaev, executed the Marathon bombings, they would present a relatively new profile for "the enemy" and mark the first successful act of "homegrown" Islamic terrorism.
Unlike earlier terrorist attacks (and several failed attempts), such the September 11, 2001 attacks on New York and Washington, or subsequent plots like those of the "shoe bomber" or the "underwear bomber," there seems little evidence that this operation was planned, directed, supported, or funded by any foreign groups. During Tamerlan Tsarnaev's six month trip to Russia in 2012 he may indeed have contacted Islamic militants -- Chechen or otherwise -- and received indoctrination, training, and support. However, his path to radicalism and violence likely predated that trip and the idea for an attack was likely well underway. These types of attacks, sometimes termed "franchise terrorism" are inspired by the ideas, messages and examples of al Qaeda and Osama bin Laden even if the specific goals or objectives may be less coherent and no direct organizational role is present.
This type of terrorism presents intelligence and law enforcement officials with somewhat of a double-edged sword. On one hand, before the Patriot's Day attack, these types of actors -- naturalized or American citizens who become radicalized -- have proven ineffective (consider the 2007 planned attack on Fort Dix and the 2012 Miami case involving two naturalized Pakistani brothers) precisely because they are not trained operatives and often seem to have inflated goals, grandiose plans and poor instincts which make them relatively easy targets for domestic law enforcement. On the other hand, these actors present a far more difficult challenge for national intelligence and law enforcement agencies precisely because there won't be any communications or "chatter" to be captured through surveillance of likely foreign sources, nor are these actors likely to have any traceable ties to known foreign terrorist networks.
As we have seen all too clearly in recent cases of mass violence in the United States, a dedicated individual or a small, coherent group (particularly like siblings or classmates) that decides to embark on this type of relatively methodical, targeted action, presents an exceedingly difficult challenge for law enforcement and intelligence and can thus be brutally effective. Like the tragedies in Newtown, Connecticut, Aurora, Colorado and Tuscon, Arizona involving individual attackers, there may simply be very little warning prior to the event that could alert local law enforcement, never mind federal law enforcement or intelligence agencies.
This is not a new problem, nor is it without solutions, but it is a difficult challenge to address. Many western European countries with large Middle Eastern, North African or South Asian communities have lived in fear of "homegrown," domestically-driven radical Islamic terrorism for some time. Again, such terrorism would need no foreign organizational participation aside from a general overarching message and examples provided by the various acts of al Qaeda. The only viable solution to the problem is to develop extensive networks of intelligence within local communities to identify radicals before they can build the capacity to act. In the United States, this is likely to be even more difficult task, but as discussions about mental health and the identification of potential violent actors continues in the wake of recent mass-killings, resources for the development of intelligence capabilities at the local and state level should certainly be at the forefront.