There's no such thing as a perfect solution to Syria's crisis, so any path President Obama takes will naturally draw criticism for its shortcomings. His administration's current approach, to seek a U.N. Security Council resolution to remove Syria's chemical weapons, has plenty of those: It could be spiked by Russia at any moment; it does nothing to shape the course of a bloody civil war; and, maybe the bitterest pill of all, it implicitly suggests to Syrian leader Bashar al-Assad that he can keep killing civilians without fear of U.S. reprisal as long as he kills them with conventional weapons.
Still, there's one argument against Obama's approach that's generating increasing attention but maybe shouldn't be. The case goes like this: Obama has previously called on Assad to step down. But if he strikes this deal for the removal of Syria's chemical weapons, he'll be implicitly acknowledging Assad's authority and thus conferring greater international legitimacy on the Syrian dictator, thus undermining his own effort to isolate Assad.
The problem with this argument is that Obama never actually sought to remove Assad from power against his will and has consistently acknowledged him as Syria's head of state. Before the crisis began in 2011, Obama sent the first U.S. ambassador to Syria in several years, a short-lived attempt to engage Assad. After Syria began its violent crackdown on the 2011 pro-democracy protests, Obama did call on Assad to step down.
Since autumn 2011, though, events in Syria have changed pretty dramatically. Obama's position hasn't changed, exactly, but it's certainly become more specific. For months, he and his administration have been emphasizing that the United States does not want to see Assad toppled outright, which officials believe would just make Syria's crisis worse. What the United States wants, what Obama wants, is for Assad to step down voluntarily as part of a negotiated peace deal with the rebels that would also leave elements of Assad's government intact.
Obama's thinking is that Assad himself has to go but that Syrian society is so badly broken right now, and that these social fissures are such a big part of the conflict, that the country simply can't afford to rebuild a government from scratch. This plan makes sense, but it does require acknowledging Assad as Syria's official head of state and head of government. All of which is to say that Obama's chemical weapons plan would not actually change his position on Assad's legitimacy one bit.
If it surprises you to learn that Obama wants Assad to step down only voluntarily and for parts of his regime to stay on, that may be because Obama has not done much to push this deal through. Partly that's for practical reasons: Assad hasn't shown any willingness to negotiate, and it's not clear who would negotiate for the rebels. But partly it's also because the Obama administration has not taken any action to force Assad to the negotiating table, either because it believes nothing would work or because it believes it's simply not worth it.
The administration, naturally, is not eager to call attention to this negotiated peace goal that it's doing little to make happen. That's probably even more true right now. A chemical weapons deal, for all its benefits, could make it tougher for the United States to coerce Assad into accepting Obama's negotiated peace plan. Assad could safely conclude that the United States will not use military force against him as long as he continues very slowly winning by using conventional rather than chemical weapons.
So, yes, a chemical weapons deal has some real downsides. But conferring legitimacy on Assad is not one of them, because this would not actually mark a substantial change in Obama's position on Assad's legitimacy as the Syrian head of state.