Aaron David Miller nominates Syrian “safe zones” as one of the five dumbest ideas in recent times:

Dumb ideas are one thing; potentially dangerous ideas are quite another. And that distinction goes to the idea of creating safe zones in Syria in an effort to pressure, if not topple, the regime of Bashar al-Assad. The proponents of this idea are either interminably obtuse or quite calculating and see the creation of such zones as a way to sucker the United States or other external powers into military action against the Assads. Either way, this approach has every sign of being half-baked, ill-advised, and open-ended. Indeed, it’s driven by the most dangerous idea of all: that America needs to act and do something, regardless of the consequences.

I assume that the very half-baked nature of the measure is why some interventionists find it so attractive, so I guess the proponents fall under the “quite calculating” category. A “safe zone” lowers the barriers to outside military action, which broadens political support for it. It creates the illusion of a “limited” intervention, which guards against accusations of entangling the U.S. in a quagmire. It maintains the fiction that using force in Syria still has something to do with protecting civilian lives, when it will in all likelihood set up indefensible places for opposition forces to gather where they will become even easier targets.