A lot of people seem to have woken up today and realized that it's really, really hard to destroy tons of chemical weapons during a civil war.
That's true! You can read just how hard it is here and here. In fact, it's really hard to destroy tons of chemical weapons when there's not a civil war! Just ask the United States: We agreed to get rid of our chemical weapons stockpiles in the 1990s and we're still only 70 percent done.
So yes, it will likely take a long time to destroy Assad's entire chemical weapons arsenal, if it ever happens at all. But the alternative is air strikes. And we know air strikes won't destroy any of Assad's chemical weapons stockpiles, as when you hit chemical weapons with a missile, deadly gas goes everywhere and kills innocent civilians.
That means the choice is between air strikes that won't destroy any of Assad's chemical weapons (unless, tragically, we miss) and a negotiated process that has the potential of eventually destroying all or most of them. The choice there seems clear.
This argument that the only viable deal is one in which Assad destroys all his chemical weapons pretty much immediately represents a massive shifting of the goal posts. The argument for air strikes was that merely they'd persuade Assad to stop using his chemical weapons. Judged on that score, the Russia-Syria deal looks even better.
Assad will be voluntarily committing to giving up chemical weapons, his patron Russia will have put it credibility on the line behind Assad giving up chemical weapons, and the United States would have an easier time mustering international support for air strikes if Assad used chemical weapons. Conversely, in the event of air strikes, Assad might use chemical weapons either to demonstrate defiance or because the strikes tipped the scales against him and he's now more desperate.
The good argument against this deal is the one that Sen. John McCain hinted at earlier today: If you want the United States to get more deeply involved in Syria's civil war and really commit to undermining Assad, any deal with Russia and Syria probably makes that impossible. But if you don't want to see the U.S. more deeply involved in Syria and you just want the cause of banning and destroying chemical weapons advanced, the deal seems like a clear winner, even if the U.S. doesn't get everything it wants on the wording of the resolution.