Some people are comparing Syria to Iraq, saying it's the same situation again. But it clearly is not.
In Iraq there was a question of whether Saddam had WMDs (and it was known that he didn't have nukes, with only the flimsiest of evidence that he wanted to produce them someday). In this case it's a known fact that Assad has chemical weapons (which is in the WMD category, although it seems like the title Weapons of Mass Murder seems more appropriate, given its lack of effect on infrastructure) and that a chemical weapon attack occurred; the only dispute seems to be whether Assad personally ordered the attack.
In Iraq there was peace (although the country was, for some, a bad place to live). In Syria there is an ongoing civil war that has already killed over 100,000 people and displaced a third of the population. America's invasion crippled the Iraqi government and some critical infrastructure (and opened the floodgates for terrorism); but Syria is already unstable.
So some arguments that would have made sense against the Iraq war don't make sense against a strike against Syria. On the other hand, there are clearly still various arguments we can make against even targeted strikes on Syria (let alone full-scale war):
- Syria has powerful allies, especially Russia but also Iran and China (read about the reasons for this). Without evidence to the contrary, I'd assume military action in Syria could lead to broader hostility with these allies. Who can promise we won't have a World War 3?
- Assad, not unlike Saddam Hussein, may be a douchbag. But as with Iraq, we might not like the alternative. Removing Hussein led to terrorism in vast quantities in Iraq (and even the good guys sometimes behaved badly); the confirmed death toll has exceeded 100,000 people. Similarly, besides Assad there are multiple factions in Syria that are basically enemies, and no reason to expect stability once Assad is gone. There is no way to control who takes his place, and it is not clear that the West should be allied with any one of the opposition groups.
- The U.S. is not the world's policeman, and its past behavior (as well as ongoing developments like the NSA mass spying programs) has not earned the U.S. the respect it would need to successfully take that role. If anything, the U.S. is known for consistently not taking the moral high ground, but for just pretending to.
I appreciate Obama's argument that a chemical weapon attack--which breaks the international "taboo" on the use of WMDs--could be a slippery slope that leads to further use of chemical weapons in the future, if the international community does not respond with some sort of force to show that this behavior is unacceptable (even during a war). But if the U.S. responds alone or with only a few allies, it will not send the right message--it'll just look like another episode of "Team America, World Police" instead of the chorus of international condemnation against chemical weapons that we should be seeing.
Partly, that's why I'm supporting Avaaz's petition for diplomatic solutions in Syria. And partly, I'm supporting the petition because war is always, always, always risky, messy business that we shouldn't rush into.