Being cautious on Syria is still the best approach for the Obama administration, and here’s why.

It’s working.

The Assads are going down, though not nearly as quickly as one might have hoped. The opposition has now put both Damascus and Aleppo in play, testing the Syrian military’s control of the country’s two major cities. The Assads’ already small circle of key advisors has been reduced as a result of the July 18 bombing in Damascus that killed four top security officials. A grave sense of vulnerability and pervasive suspicions over whom to trust will continue to take its toll on the rest of the family’s circle. The regime’s counter-crackdown, meanwhile, is only deepening the rebels’ determination to resist and enlarging its pool of recruits. Meanwhile, the Syrian army continues to become fatigued and demoralized by endless guerrilla warfare against an enemy that appears to be simultaneously everywhere and nowhere.

This process will not be quick or painless. But nobody has made a compelling case that half-measures — more arms for the opposition, no-fly zones, safe havens — will bring the Assads down. To give these ideas the old college try because we feel compelled to “do something” isn’t a strategy; it’s a wing and a prayer. And after Iraq and Afghanistan, it’s just not good enough to pass the threshold for putting American lives, money, and credibility on the line.