Again, I am very uncomfortable with the idea that I might sound like I'm trying to diminish the guy's crimes. He committed treason and murder. It was a cowardly act. If we are at war, then it was a war crime.
But I think the reader's definition of terrorism might move us into dangerous territory. In Pakistan, we launch missiles at people's homes with civilians in or around them to take out al-Qaeda leadership. The attacks are — hopefully — always intended to be something of a surprise. But I wouldn't call that terrorism. I'm just uncomfortable with the word terrorism metastasizing into "anything the bad guys do to us." Why not call what Hasan did a war crime? Terrorism is a war crime but not all war crimes are terrorism.
Of course, the fact that Jihadis reject all of the rules of war makes it very difficult to figure out how to even talk about the rules. (Just out of curiosity, what would the legal definition be of, say, a Japanese officer turning on fellow Japanese troops during World War Two in the apparent hope of aiding the Allies?)
As I said before, if terrorism is now the catchall for dastardly acts committed by Jihadis, then calling this attack terrorism works fine for me. But if this is really a war — and I think it is — then I think we could spend some more time thinking a bit more rigorously about our vocabulary. For those interested, this is a longstanding interest of mine.