> Assad has killed about half a million Syrians already in the civil war.

How can that be true? Western academics protest when so many people are killed. The Gaza health ministry itself claims less that 1/10 of that number, and look at how many protests and riots are in the US right now. If Syria really had half a million dead you'd see the academics rioting about that.

The definition of terrorism generally excludes acts performed by a legitimate state. Whenever this causes problems, you have to declare the relevant state illegitimate (which, depending on the state, may be trivial or highly contested).

It's also been standard practice in war since pretty much forever. Not that that's a good thing—war is and always has been terrible—but Israel didn't invent the idea of targeting civilians, nor are there any countries in recent history who have suddenly become above that kind of warfare. There are some that like to talk the talk, but they either have managed to just avoid war (to be fair, good on them) or do the same thing.