WASHINGTON Terrorism is speech speech that gathers its audience by killing innocents as theatrically as possible. The 19th-century anarchist Paul Brousse called it "propaganda by deed." Accordingly, the Boston Marathon attack, the first successful terror bombing in the United States since 9/11, was designed for maximum effect. At the finish line there would be not only news cameras but also hundreds of personal videos to amplify the message.
But what message? There was no claim of responsibility, no explanatory propaganda.
And even though we know who did it, at this writing there still is no definitive explanation. The Tsarnaev brothers are Chechens. The older one appears to have become radicalized. He is reported to have shared radical Islamic videos urging jihad. One, for example, that showed bombs exploding was captioned "then Allah will rise an army from the non-Arabs … their weapon will be the weapon of faith."
Uncharacteristically for Islamist terrorism, however, the Boston bombing produced no claim of responsibility.
What does this mean?
There was much ado about President Obama's nonuse of the word "terrorism" in his first statement to the nation after the bombing. Indeed, the very next morning, he took to the White House briefing room for no other reason than to pronounce the event an "act of terrorism."
There was no need to be so sensitive about the omission, however. The president said that terrorism is any bombing aimed at civilians. Not quite. Terrorism is any attack on civilians for a political purpose. Until you know the purpose, you can't know if it is terrorism.
Sometimes an attack can have no purpose. The Tucson shooter who nearly killed Rep. Gabrielle Giffords was simply deranged, a certified paranoid schizophrenic. Or there might be some personal vendetta a purpose, but not political.
In this case it's extremely improbable. (Schizophrenics are too disorganized to set off simultaneous bombs, for example.) It's overwhelmingly likely that the Tsarnaev brothers were politically motivated.
Why was the president sensitive about his nonuse of the word "terrorism" in the first place? Answer: Benghazi. There, the administration had been roundly and correctly criticized for refusing to call it terrorism for so long.
Regarding Benghazi, however, the word mattered. The administration tried to peddle the story of a spontaneous demonstration, rather than a terrorist attack, in order to place the blame on a mob incited by a nutty Coptic American who had made an offensive video. This would have spared the administration any culpability.
In Boston, in contrast, there never was any question about deliberateness. Here, the linguistic challenge for the president is quite different. What if this was an attack inspired by Islamist ideology?
Most Chechen terrorism has been nationalist and aimed at Russia, which has twice waged war and is now engaged in a counterinsurgency to suppress Chechen separatism. Some of the most gruesome terrorist attacks of our time the attack on a Moscow theater and on Beslan's School No. 1 were the work of Chechen separatists.
But many other Chechen fighters are religiously oriented, having enlisted in the worldwide jihad and fighting in Afghanistan, Iraq, the Balkans, some reportedly now in Syria.
If the Tsarnaevs are anti-Russian nationalists, it's hard to see why they would be attacking American civilians. It's far more likely that their motive was Islamist.
And here the president faces a challenge. Will Obama level with the American people and use the word? His administration obsessively adopts language that extirpates any possible connection between Islam and terrorism. It insists on calling jihadists "violent extremists" without ever telling us what they're extreme about. It even classified the Fort Hood shooting, in which the killer screamed "Allahu Akbar" as he murdered 13 people, as "workplace violence."
In a speech just last month in Jerusalem, the president referred to the rising tide of Egypt's Muslim Brotherhood and other Islamists as the rise of "non-secular parties."
Non-secular? Isn't that a euphemism for "religious," i.e., Islamist?
Yet Obama couldn't say the word. This is no linguistic triviality. He wouldn't be tripping over himself to avoid any reference to Islam if it was insignificant.
Obama has performed admirably during the Boston crisis, speaking both reassuringly and with determination. But he continues to be linguistically uneasy. His wavering over the word terrorism is telling, though in this case unimportant. The real question is: If it turns out that the Tsarnaev brothers were acting in the name of jihad, will the president forthrightly say so to the American people?
Charles Krauthammer's email address is email@example.com.