After 9/11, protesting the Afghanistan invasion (though some did!) was insanity barely worth acknowledging. WE were "hit" so OF COURSE we have THE RIGHT to respond.
And, well, ok, sure, even this peacenik can see that a military response to a mass murder of that scale shouldn't be off the table.
But to what end? What actually did we hope to achieve? What could it achieve? And at what cost (money, lives - "theirs" and "ours")?
Memory imperfect, but it didn't take too long to realize nobody had any answers at all to those questions. "Get Bin Laden and the bad guys," I guess, which morphed into "don't allow a safe haven for terrorist training camps." And (even leaving aside that little Iraq thing) we spent years bombing and droning (thanks, Obama) "terrorist training camps" all over the place which is quite obviously stupid (worse than stupid). Guy whose job is justifying his salary and finding targets kept finding them!
Anyway, if you punch me I suppose I have a "right" to punch back, whatever that means. Maybe I even have the "right" to level your entire block. But to what end?
De-escalation should always be the goal, and that has little to do with who is right and who is wrong, ultimately.