The guy flies an airplane into a federal building.  In the online note he left behind, he wrote:

I know I’m hardly the first one to decide I have had all I can stand. … I can only hope that the numbers quickly get too big to be white washed and ignored that the American zombies wake up and revolt; it will take nothing less. I would only hope that by striking a nerve that stimulates the inevitable double standard, knee-jerk government reaction that results in more stupid draconian restrictions people wake up and begin to see the pompous political thugs and their mindless minions for what they are. Sadly, though I spent my entire life trying to believe it wasn’t so, but violence not only is the answer, it is the only answer.

And the Homeland Security officials release a statement saying:

“We believe there’s no nexus with criminal or terrorist activity”

Excuse me, but it was terrorism.  Maybe not international terrorism, but terrorism nonetheless, even by the FBI's twin definition of terrorism:

Domestic terrorism refers to activities that involve acts dangerous to human life that are a violation of the criminal laws of the United States or of any state; appear to be intended to intimidate or coerce a civilian population; to influence the policy of a government by mass destruction, assassination, or kidnapping; and occur primarily within the territorial jurisdiction of the United States. [18 U.S.C. § 2331(5)]

International terrorism involves violent acts or acts dangerous to human life that are a violation of the criminal laws of the United States or any state, or that would be a criminal violation if committed within the jurisdiction of the United States or any state. These acts appear to be intended to intimidate or coerce a civilian population; influence the policy of a government by intimidation or coercion; or affect the conduct of a government by mass destruction, assassination or kidnapping and occur primarily outside the territorial jurisdiction of the United States or transcend national boundaries in terms of the means by which they are accomplished, the persons they appear intended to intimidate or coerce, or the locale in which their perpetrators operate or seek asylum.