Losing our foothold "in the grim effort to prevent the slide down the slippery slope to war"

On its own, the decision will have only a marginal impact on the Syrian war -- the real risks lie in what steps might follow when it fails. The significant moves to arm the rebels began last year, with or without open American participation. Assad's brutal campaign of military repression and savage slaughters and the foreign arming of various rebel groups has long since thoroughly militarized the conflict. The U.S. is modifying its public role in a proxy war in progress, providing more and different forms of support to certain rebel groups, rather than entering into something completely new.

The real problem with Obama's announcement is that it shatters one of the primary psychological and political footholds in the grim effort to prevent the slide down the slippery slope to war. He may have chosen the arming option in order to block pressure for other, more direct moves, like a no-fly zone or an air campaign. But instead, as the immediate push for "robust intervention" makes obvious, the decision will only embolden the relentless campaign for more and deeper U.S. involvement in the war. The Syrian opposition's spokesmen and advocates barely paused to say thank you before immediately beginning to push for more and heavier weapons, no-fly zones, air campaigns, and so on. The arming of the rebels may buy a few months, but when it fails to produce either victory or a breakthrough at the negotiating table the pressure to do more will build. Capitulating to the pressure this time will make it that much harder to resist in a few months when the push builds to escalate.