As President Trump threatens a major escalation in Iran, signs are mounting that the U.S. military is preparing for a potential return to major military operations. But experts are skeptical that an intensified air strike campaign — even if it takes out bridges, water facilities and electricity plants — will break Tehran or force tough concessions at the negotiating table. "I don't think it will change Iran's calculation in any way, because from Iran's perspective, this is when they said it publicly, that this is a war of survival for them. So bombing from the air is not going to...