A software engineer furious with the Internal Revenue Service plowed his small plane into an office building housing nearly 200 federal tax employees on Thursday, officials said, setting off a raging fire that sent workers fleeing as thick plumes of black smoke poured into the air.

A U.S. law official identified the pilot as Joseph Stack and said investigators were looking at an anti-government message on the Web linked to him. The Web site outlines problems with the IRS and says violence “is the only answer.”

Per the Austin American-Statesman, it appears, thankfully, Stack failed to kill anyone.

There is not a credible definition of terrorism that does not include the act of flying a plane into a building filled with civilians as a political statement. Stack is evidently not religiously motivated, but that does not change the definition at all. If he acted alone, then he’s what the Department of Homeland Security has recently taken to calling a lone-wolf extremist.

I suspect that the Austin police are saying — as this photo caption indicates — that this isn’t an “act of terrorism” as a shorthand to distinguish the attack from the work of al-Qaeda. And lord knows that “terrorist” and “al-Qaeda” have been conflated so often in the last nine years. But the distinction is important. Not every act of terrorism is religiously oriented. Some terrorism is the work of home-grown extremists who have nothing to do with religion, nothing to do with American foreign policy, and certainly nothing to do with Islam. Some of it, of course, will be. But that shouldn’t diminish from our ability to describe events as precisely as we can, especially if we’re going to continue to live in an age where the ubiquity of concerns about terrorism is the new Normal. And here the designation fits.

Update: More from Lady Z.

Update 2: At the risk of retreating to lexicography, the FBI’s definition of domestic terrorism would appear to fit this case:

Domestic terrorism is the unlawful use, or threatened use, of force or violence by a group or individual based and operating entirely within the United States or Puerto Rico without foreign direction committed against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof in furtherance of political or social objectives.