If we treat this like a reasonable response, then we'd just be incentivizing everyone to start more and more terrorism every time collateral damage kills some civilians despite trying to minimize it. Why don't Karelians start a terrorist campaign against Russia? Why don't any other occupied peoples start terrorism campaigns, if that's the most effective way to go? Maybe Catalonia should start terrorism, and the Basques ought to go back to it? Maybe Native Americans? Oh wait. There is one big difference between all these peoples and the Palestinians.