In fact, it’s hard to discern any principle that distinguishes killing Assad from the targeted assassinations and humanitarian wars that command significant American political support. A key principle of just-war theory is the principle of discrimination: You should tailor your violence as narrowly as possible. Some justify drone strikes on exactly those grounds: They hurt fewer people than the full-scale invasions the U.S. launched in Afghanistan and Iraq. The same principle applies to sanctions: Most people would agree that sanctions that target a ruling elite are preferable to ones that affect an entire people. If that’s the case, then why isn’t it preferable to target Assad personally instead of bombing Syrian conscripts, or Syrian civilians, in order to bring down his regime?

Let me be clear: I’m not proposing that we try to kill Assad, nor even that we outsource the job to a local ally like Jordan. For one thing, it might not do much good. Syria is ruled less by Bashar al-Assad himself than by an Alawite clique willing to commit terrible crimes because they like the perquisites of power and fear for their community’s safety if they give up that power. Kill Assad, and some brother, cousin or allied general might take over where he left off.

But the larger question is how far we’re willing to go in prioritizing American security interests and humanitarian ideals over national sovereignty and international law.