Over at foreignpolicy.com, Andrew Tabler has posted a piece with this pithy billing: "The United States needs to tell the Syrian regime in no uncertain terms: Use chemical weapons and we will end you."
Assad would probably use chemical weapons only if he felt cornered--felt as if failing to use them would spell doom for his regime and/or him. So it's not as if he'd see the choice of whether or not to use chemical weapons as being between death and life. He'd see the choice as being between one path to death and another path. What's more, since the U.S. threat to end the regime could require a ground invasion for its realization, and America isn't exactly looking for new ground invasions to lead, Assad might think the one path to death--the path of using chemical weapons--would stand some chance of not actually leading to death.
One obvious way to strengthen the incentive structure would be to pose a cornered Assad with a different choice: If you don't use chemical weapons, and just give up power peacefully, you can have a long and happy life.
But it's hard to offer him that option, because the Syrian army has already committed enough atrocities to get Assad indicted and convicted by an international tribunal and locked up for the rest of his life. So, to him, surrender may seem to entail a fate not much more attractive than death.
This has actually been a problem for awhile now. There's been talk of a "negotiated deal" with Assad, but the number of civilians killed by his regime long ago passed the point where it seemed plausible for such a deal to wind up with him easing gracefully into a pleasant retirement in some nice villa on the Mediterranean. His choice has long seemed to be between continuing to fight and accepting no-frills retirement in a prison cell.
I'm in general a big fan of global governance, and that includes global judicial mechanisms for punishing war crimes. But it may make sense to think about making these mechanisms more closely parallel with national judicial mechanisms than they are now. That is: authorize plea bargaining.
Suppose that, 10,000 Syrian lives ago, we could have offered Assad the option of safe haven if he surrendered power peacefully. Or, maybe, we could have offered him the option of safe haven after serving a year of jail time. Or two years, or whatever.
Now, you might argue that to let him off that lightly would have been to dishonor the 8,000 or so Syrians who had already died. Point taken. But tell that to the other 10,000. And tell that to the many thousands who may die yet.
If you want to hear two people who are more expert in this area than me discuss this very issue, here's an excerpt from an exchange that took place three weeks ago on the BhTV show Foreign Entanglements: