Some say don't interfere. It's an Arab thing. It doesn't concern us. I disagree. When innocent people are being massacred by their own government, it's a humanitarian issue - i.e., a human issue. This is our planet. We are humans. And I don't think we should allow senseless killing to occur against innocent people.
Of course, it isn't that simple. Quite sensibly, several countries are anxious and resistant to the idea of US intervention. We have been known to interfere with foreign politics (elections, governments, coups, etc) in the past, to say the least. Furthermore, invading Middle Eastern countries tends not to work out for us in the long run - or for the indigenous peoples.
But we cannot simply watch while innocent people are slaughtered. That is out of the question. The question is what do we do?
Unilateral action, the US acting alone, I wouldn't recommend. I do not believe the US, even as arguably the strongest military power on earth, is the world's policeman. I do believe foreign nations' sovereignty should be respected and we should not interfere with their governance or try to pick and choose who we want to rule other countries, as we've done. However, something, obviously, should be done. The problem with going it alone is that it's not our place. It is not our sole responsibility. We all, as humans, share in the responsibility of helping those who can't help themselves when we can do something about it.
Bilateral action is what I'd recommend, a collective action, involving several nations, that demonstrates the transcendence of this issue beyond politics or imperialism. If this can be done through the UN, great. If through some other union or alliance of nations, that's great, also.
But what exactly should we do?
Diplomacy is certainly preferred to violence, but I remember wondering, watching Kofi Annan talking with Assad, before Annan had to resign as special envoy to Syria because of the futility, what they were talking about. I mean, how exactly are you supposed to talk a brutal dictator out of massacring his own people? "Um, Mr. Assad, could you please stop killing your people?" "No, thanks."
Sanctions are a good start. Economic sanctions (such as those employed by the EU early on) I think, are the best way to persuade dictators. Morals may not move them, but money likely will. (They tend to live pretty lavishly, after all.) If the sanctions are significant enough, involving as many nations as possible (preferably with Russia and China) and being immediate and serious, we might see some attempt at being reasonable on the brutal regime's part. Otherwise, power concedes nothing.
But what if the killing continues? Then we need to gradually escalate the seriousness of our collective action. People are being killed. There is no time to waste. The sanctions ideally would become more severe until they reach their limits of usefulness.
Military action would have to be taken if, after exhausting all peaceful methods, people are still being killed. I also think this should be done on a gradual scale of increasing intensity. A no-fly zone is a good place to start at. Then, if that doesn't work, possibly arming the rebels. (The US promise of arms has yet to reach the rebels.) Then air strikes. And if all else fails, which I don't think would happen, troops on the ground. We must protect the innocent if we protect anyone. (However, the rebels themselves have been accused of wrongdoings.)
We need a precedent, a plan of action when these things occur. This is not about Iran. It's about innocence. We cannot afford to wait while innocent people are being massacred, especially when chemical weapons or weapons of mass destruction are being used. We also need the courage to commit to such action.