(This post is from our new blog: Unofficial Sources.)

On April 19, 2013, as Dzhokhar Tsarnaev lay bleeding in a backyard in suburban Watertown, Massachusetts, he used his remaining energy to scrawl a note on the inside of the dry-docked boat in which he was hiding. To this day, it stands as his only publicly stated motive for the Boston Marathon bombing:

“The US Government is killing our innocent civilians but most of you already know that … I don’t like killing innocent people it is forbidden in Islam but due to said [unintelligible] it is allowed … Stop killing our innocent people and we will stop.”

Last week, just over two years since that note was written, a jury sentenced Tsarnaev to death for his role in the bombing. Speaking to the press outside the John J. Moakley courthouse in Boston, U.S. Attorney Carmen Ortiz said, “We are not intimidated by acts of terror, or radical ideals,” and described the marathon bombing as “a political crime, designed to intimidate and coerce the United States.”

Tsarnaev will soon be transferred to the federal death row penitentiary at Terre Haute, Indiana. Only 21 years old, he will likely go through a decadeslong process of appeals before a final determination is made as to whether he will be executed.

Even as his trial concludes, Tsarnaev himself remains something of an enigmatic figure. How did a popular, seemingly well-adjusted teenager who was beloved by many of those who crossed paths with him end up committing an act of indiscriminate violence in the city where he was raised? How could someone whose life was filled with so much promise end up sacrificing his future as he did?

In the course of their arguments, the prosecution and defense in Dzhokhar’s case offered two competing narratives for the events that led to his involvement in the bombing.

In the prosecution’s telling, Tsarnaev was a committed “holy warrior,” who had indoctrinated himself with radical ideological material such as Inspire magazine and the lectures of the late Yemeni-American cleric Anwar al-Awlaki. He was, in the most straightforward sense, a terrorist. As Assistant U.S. Attorney William Weinreb put it, Dzhokhar was “killing Americans here to compel the United States to stop killing terrorists abroad.” To help buttress this narrative, the government solicited highly paid terrorism experts to help draw a connection between Tsarnaev and militant groups such as al Qaeda. Matthew Levitt, a fellow at the Washington Institute for Near East Policy, would testify that Tsarnaev’s handwritten note, in which he expressed a political motive for the bombing, was “what makes it terrorism, and not just murder.”

The defense tried to dismiss Tsarnaev’s self-professed political beliefs as immaterial and not sincerely held. Arguing that Tsarnaev was simply a “good kid” who had been led astray by the influence of his unhinged, violent older brother, his lawyers sought to portray Dzhokhar as the unfortunate product of a chaotic and neglectful family.

The version of Dzhokhar put forward by his lawyers was purely apolitical. He had made a poor decision in haste, while under the pressure of the more dominant Tamerlan. He didn’t read militant literature, and what documents he may have possessed were simply pressed on him by his extremist brother. Indeed, the defense attempted not only to separate Dzhokhar from the War on Terror, but also from Islam, drawing a contrast between him and Tamerlan, whom they portrayed as more religiously devout, and correspondingly more dangerous.

But while Dzhokhar did undoubtedly come from a troubled family rife with social dysfunction and mental illness, that does not come close to offering an all-encompassing explanation for his act. As the prosecution accurately argued, the overwhelming majority of children raised in dysfunctional families do not go on to commit violence, and many of them ultimately transcend the circumstances of their upbringing completely.

So what can explain what Dzhokhar did?

Terrorism is a complex social phenomenon. It is not monocausal, and is driven partly by ideological factors, structural inequities and feelings of moral or political grievance. But in order to have a full explanation of what led to the 2013 marathon bombing, it is important to take seriously Tsarnaev’s own stated motivation — which echoes that of many other homegrown terrorists — as well as look at the underlying political context in which his crime was committed.

In Tsarnaev’s note, he alluded to a type of transnational solidarity felt among Muslims living under oppression, writing, “I can’t stand to see such evil go unpunished … we Muslims are one body, you hurt one you hurt us all.” While his lawyers attempted to downplay this statement as immaterial, it echoes the statements of many others convicted of terrorism offenses in the United States.

At the conclusion of his trial, would-be Times Square bomber Faisal Shahzad gave a statement saying, “I am part of the answer to the U.S. terrorizing the Muslim nations,” and added that attacks such as his would continue “until the hour the U.S. pulls its forces from Iraq and Afghanistan and stops the drone strikes in Somalia and Yemen and in Pakistan.” Zarein Ahmedzay, convicted for his role in a separate plot to target the New York subway system, stated that “I personally believed that conducting an operation in the United States would be the best way to end the wars.”

Despite the obfuscations of many American politicians and media figures, the civilian deaths cited by such homegrown terrorists are not imaginary. This past March, the Nobel Prize-winning group Physicians for Social Responsibility published a landmark study on civilian deaths caused by the post-9/11 War on Terror. The study, which tabulated death tolls from U.S-led military interventions in Iraq, Afghanistan and Pakistan, determined a conservative estimate of civilian deaths at 1.3 million as a result of these operations, with the actual death toll potentially in excess of 2 million. Writing that “the more the consequences of Western military interventions as well as the resulting casualty figures can be hidden and played down … the more easily new interventions can be ordered,” the study’s authors went on to note that their rigorously documented figures were more than 10 times higher than those commonly referenced in public discourse.

Tsarnaev, like Shahzad, Ahmedzay and countless other homegrown terrorists, cited these deaths as a motivation for his act. His actions, which killed and maimed hundreds of innocent civilians who had no direct connection to any American military intervention, was heinous, immoral and unjustified. But to take him at his word, he perceived it as a response to a moral grievance which is broadly felt by hundreds of millions of people around the world. While Tsarnaev’s own personal life may have contained enough dysfunction to have pushed him toward expressing his dissent in such a gruesome fashion, it is worth reflecting upon whether he or his brother would have gone down such a path in the absence of an open-ended global war against a community with which they identified.

Neither the prosecution nor defense had any incentive to engage with this question at Tsarnaev’s trial. And of course, the larger U.S. government may simply perceive attacks like the Boston bombing as “a small price to pay for being a superpower.”

Regular people who don’t want to pay that price do have such an incentive, however. Until we begin to seriously address the wars and civilian deaths cited as grievances by individuals like Tsarnaev — grievances that are both real and potentially powerful enough to turn well-adjusted, law-abiding young men into killers — the phenomenon of domestic terrorism will likely continue to accelerate, and there will be, inevitably, another Dzhokhar Tsarnaev.

Photo: Jane Flavell Collins/AP