This story from Fox News points out how quick authorities in Texas were to confidently stand before reporters and say that a plane crashing into an IRS building in Austin wasn't terrorism. I'm not so confident of that. What was Joseph Stack's intention? I would argue that it's very possible his intent was to strike terror into the hearts of those who worked at the IRS building. I don't believe an attack has to be part of a larger conspiracy to be terrorism. And just because this incident lacks the threat of further violence, as is typically the case in Islamic-extremism terrorism, I don't think that disqualifies this as terrorism either.
My definition of terrorism is an acting with the intent to terrorize. Whatever desperation drove Stack to commit suicide in the fashion he did, I believe that was his intent. That doesn't change the fact that Islamo-extremism terrorism is the greatest terror threat this country faces, by far. AI don't know that I've reached a conclusion yet, but I disagree with authorities in Texas so quickly proclaiming this wasn't terrorism.