Terrorism or not?

Today a guy crashed his single-engine plane into the IRS building in Austin Texas because he was angry with the government and its tax policies.

Horrible tragedy, and I worry that it will lead to more senseless and ineffective restrictions on our freedoms (particularly freedom to fly), but what caught my attention here was something more academic.

Officials took pains to stress that this was a criminal act and by and large studiously avoided the "T" word - "Terrorism." Interesting that they should do so. I wonder why? This looks and feels like domestic terrorism to me.

The word "terrorism" is notoriously difficult to define. I've always used as a basic sniff-test definition any act of violence that is specifically targeted against civilians or non-combatants for the purpose of making a political statement.

By that definition, I can't see any semantic distinction between what Joe Stack apparently did today and what 19 Saudis did on Sept 11 2001.

Perhaps my definition is inadequate? I've tried on a number of variations of the term, but I have found none that classifies 9/11 as "terrorism" yet excludes today's event and still works for other "obvious" examples of terrorism.

For example, if one insists on the presence of religion, which does distinguish 9/11 from today, then one must conclude that Timothy McVeigh and the Unabomber were not terrorists.

Today's events do appear to be more out of personal revenge than to advance a broader cause, but even that feels more like a matter of degree, not a fundamental distinction. And after all, crashing a plane into a building with hundreds of people inside sends a very broad message of intimidation and fear regardless of whether that was explicitly intended.

I'm curious if any of my readers have a definition of terrorism that yields a positive match results for "obvious" terrorism cases like 9/11 or Timothy McVeigh, yet yields a negative for today's sad events.