I don't think this is terrorism, that's not what the word means. It's a clear and open act of war, so in many ways much worse, but somehow terrorism is a scarier word.

> but somehow terrorism is a scarier word.

It is, because it might impact normal citizens. Nobody has ever invaded the US so coensequences of real war are unknown to most.

> Nobody has ever invaded the US

That's not technically true, seeing as how Washington DC was captured and burned in 1814. But it's at least true for modern times.