Speculating about who carried out the Boston Marathon bombing

In the aftermath of yesterday’s terrorist bombing in Boston, I’ve been surprised to hear many commentators warn against "speculating" who may be responsible. That’s nonsense. Of course we should speculate: That’s the first step in formulating a hypothesis to guide an investigation that will lead to facts. The facts may disprove our speculation, but we simply can’t skip the first step. So here are some initial hypotheses, in descending order of plausibility. Most of these will later be proven wrong.

1. Al Qaeda, or a copycat jihadist group, did it.

• AQ and its sympathizers have been trying to kill Americans for 15 years and have a long track record of attempted and successful attacks.
• A double-bombing fits AQ’s modus operandi.
• This is one of the two most-likely hypotheses. Against this hypothesis: There’s been no claim of responsibility yet, which is unlike AQ. They’re generally loud and proud about their killing. Also, according to former Secretary of Defense Leon Panetta, al Qaeda is nearing "strategic defeat." A successful attack on the U.S. homeland would suggest otherwise. Could Panetta be wrong?
• Variant: This might have been the work of a lone jihadist sympathizer, like Nidal Hassan (the man charged with the 2009 Ft. Bragg shootings), which would account for the lack of a claim of responsibility. That would also account for the seemingly greater local knowledge displayed in this attack.

2. North Korea did it. 

• North Korea was a designated state-sponsor of terrorism from 1988 to 2008 for a series of terrorist bombings and kidnappings against South Koreans and Japanese in the 1980s and 90s. The White House was recently weighing whether to re-designate the state because of its continued lack of cooperation against terrorism.
• North Korea has undertaken a couple of brazen, unprovoked attacks on South Korea in recent years, including sinking a submarine and shelling an island in 2010.
• North Korea is in the midst of a leadership transition. Kim Jong Un has been banging the war drums for weeks to "Wag the Dog" (solidify his rule by manufacturing a foreign crisis).
• Yesterday was Kim Il-sung’s birthday. North Korea traditionally used the birthday of its founding "Great Leader" as an opportunity to display its strength with military parades and bellicose rhetoric. It was the day North Korea was widely expected to take some kind of action to deliver on weeks of threats (though most thought it would be a missile test, not a terrorist attack).
• I think this is the other most likely hypotheses. Against this hypothesis: It would be an uncharacteristic and risky escalation for North Korea to attack a U.S. target, on U.S. soil (but maybe that’s how Kim Jong Un wants to distinguish himself).

3. Several groups cooperated in the attack. 

• From 1985 to 1989, Libya orchestrated a global terrorism campaign against U.S. and western targets in Rome, Vienna, the Mediterranean, Berlin, Madrid, several airliners, Indonesia, and elsewhere. Libya often worked through proxy groups like the Palestine Liberation Front, Abu Nidal, and the Japanese Red Army to give itself some plausible deniability and, probably, to create the impression that a global anti-American coalition was rising.
• Similarly, today North Korea and/or al Qaeda may be working with other anti-American actors (perhaps even each other) — which would represent a dangerous new evolution in international terrorism.

4. Domestic right-wing terrorists did it.

• Right-wing groups have done more killing than left-wing groups in recent decades.
• Yesterday was tax day and Patriots Day, which right-wing groups might have used to symbolize a nationalistic, anti-government agenda.
• Against: Why the Boston Marathon? That doesn’t exactly scream "overbearing, tyrannical, confiscatory government." And right-wing terrorism seems to have faded in the last decade.

5. Domestic left-wing terrorists did it.

• Domestic left-wing terrorists are among the most active terrorists in the United States, according to the FBI.
• Against: Left-wingers almost certainly did not do the Boston bombing. The Earth and Animal Liberation Fronts specialize in arson and sabotage. They’re pretty careful about not killing people or animals. This bombing doesn’t fit their ideology. Other groups more comfortable with killing — the Weather Underground, Black Liberation Army, Symbionese Liberation Army, etc. — have been dormant for decades. And protesting the Boston Marathon isn’t exactly a left-wing cause.

6. Anarchist/lone nut.

• There was a spate of anarchist bombings and assassinations in the 19th century, most famously felling President William McKinley in 1901. The violence was propagated mostly by a bunch of lone nuts with addled ideas.
• Similarly, we’ve seen some fairly random, non-ideological violence in recent years, including the shootings at Newtown, Conn.; Aurora, Colo.; and in Arizona against Rep. Gabby Giffords. Perhaps we are seeing a resurgence of violence for its own sake. That would account for the lack of a claim of responsibility.
• Against: Lone nuts tend not to be very smart. The Boston bombing had the marks of some sophistication to it.