Less than 24 hours after the attack that killed at least three people and injured over a hundred in Boston, speculation has begun on whom may be responsible for this terrible act. However, the White House has stated it is treating the attack as an "act of terror." This means someone is responsible for an intentional act of violence aimed at civilians in order to further a political and/or ideological goal. Was it Al-Qaeda Central under the direction of Ayman al-Zawahiri or a "lone wolf" attack inspired by an Al-Qaeda affiliate network a la the late Anwar al-Alwaki? A domestic anti-government or white supremacist would not be out of the question either. Even Iran has been accused of bombing plots on American soil recently.
Regardless of responsibility, the attack is disturbing because it is far from unprecedented. In fact it was influenced by past and persistent terrorist tactics. The explosives themselves were relatively small and unsophisticated. Certainly the bombing was less spectacular than other synchronized attacks in Madrid, London, and Mumbai. Nonetheless, it was well coordinated and bore the signature of other guerrilla and terrorist attacks seen across the world not only seen since 9/11, but for several decades before.
Reports indicate the attack was the result of IEDs backed with ball bearings and other shrapnel to maximize damage and designed to cause truly horrific injuries to its victims. These types of explosives have plagued U.S. military and civilian personnel alike over the past decade in both Iraq and Afghanistan. Packing explosives (IEDs or otherwise) with objects to increase their effectiveness is a tactic that has been used before by terrorist groups as diverse as Hamas and the Tamil Tigers (LTTE) in Sri Lanka. The two explosives in the yesterday’s attack were reportedly placed in trash bins, a convention dating as far back as the 1970’s when the IRA unleashed a deadly three decade long terror campaign against the U.K. The effect of which is still felt in the design of London’s public works.
There are two plausible forces at work in this case: 1. terrorist tactics have become collective knowledge, enabling even an unsupported "lone wolf" to implement them or 2. an international terrorist organization has decided that small-scale attacks against soft targets is the only way to skirt tough U.S. counter terrorism measures. The latter would have frightening implications for the United States.
For years terrorism and intelligence experts have been forewarning of the threat presented by the vulnerabilities of "soft targets" in the United States. Malls, restaurants, public ground transportation, and any large public event have been cited has possible targets that could be hit by small scale attacks. It would be unfair to say that this threat has not materialized until the Boston Marathon terror attack: mass shooting incidents have been taking place in soft targets at an alarming rate over the last few years. However, a sustained terrorist campaign by even a small coordinated group with international backing could test the resilience of the U.S. public unlike ever before.