The temptation here is to follow the Clinton administration’s course — a futile salvo of cruise missiles, followed by self-congratulation and an attempt to change the topic. It would not work here. A minority regime fighting for its life, as Bashar al-Assad’s is, can weather a couple of dozen big bangs. More important, no one — friends, enemies or neutrals — would be fooled. As weak as the United States now appears in the region and beyond, we would look weaker yet if we chose to act ineffectively. A bout of therapeutic bombing is an even more feckless course of action than a principled refusal to act altogether.

A serious bombing campaign would have substantial targets — most plausibly the Syrian air force, the service once headed by Assad’s father, which gives the regime much of its edge over the rebels, as well as the air defense system and the country’s airports, through which aid arrives from Iran. But should the Obama administration choose any kind of bombing campaign, it needs to face some hard facts.

For one thing, and despite the hopes of some proponents of an air campaign, this would not be surgical. No serious application of air power ever is, despite administration officials’ claims about the drone campaign, which, as we now know, has killed plenty of civilians. A serious bombing campaign means civilian casualties, at our hands. And it may mean U.S. and allied casualties too, because the idea of a serious military effort without risk is fatuous.