What seems equally clear, however, is that when this new war goes south, public opinion will sour quickly. Our history of intervening in civil wars is abysmal. We lost in Vietnam, we lost in Iraq, and Afghanistan is still on a losing trajectory. There is every reason to believe Syria will go at least as poorly as all those failures, if not worse.

Most Americans basically understand this, I think, despite the genuine horror of the beheading videos. Now, polls show bipartisan approval for airstrikes in both Iraq and Syria, but there are reasons to doubt that will last. Support for putting American troops into combat is still fairly low and approval for this war is actually below average when taken in the context of past conflicts.

I also believe that a majority of people — and Democratic voters in particular — would have responded favorably to the president trying to calm people, reminding us that ISIS is not an existential threat, and that there are limits to American power. That was Obama’s greatest political strength, once. Instead we get macho swaggering that could have been copy-pasted from George W. Bush’s term.