I've been considering doing an extended Libya post, but I'm not sure I know where I come down on the whole mess, and I suspect I won't form a firm opinion before we have a better idea which direction it's going to go. So much of these things is in the execution.
With that in mind, I've noticed a lot of people analogizing our intervention there with a number of recent conflicts. It seems to me that these analogies are universally bad. Libya differs from other recent military engagements across several dimensions.
-First of all, there was already a war in progress. War is an inherently destabilizing state of affairs, from which all sorts of unforeseen consequences can flow. That's a pretty strong case for not starting them: unpredictable violence frustrates attempts to game events or control outcomes. But here, the outcome was already in doubt, and, as best as anyone could tell, rapidly trending towards the worst-case scenario (or close to it). Attacking Qaddafi only introduces a little more randomness into an already chaotic system.
-Libya is a very small nation, population-wise. Iraq has about thirty million people in it. So does Afghanistan. Libya, by comparison, has six million. Moreover, every indication so far is that Qaddafi has minimal support outside hired mercenaries and his tribal allies. The war in Libya might be similar in kind to past wars, but it's different in scale, and scale matters. Unfortunately, I think there's a tendency among a lot of analysts to use mental categories that overemphasize qualitative similarities while ignoring quantitative differences.
This is important because ability and capacity are two separate questions. To use a quick-and-dirty analogy: somebody who is unable to bike one hundred miles might be able to bike twenty miles with ease, or they might not know to ride a bike at all. Have Iraq and Afghanistan, et al, been failures of ability or failures of capacity? I'm not sure we know.
-There appears to be genuine international cooperation occurring. It's impossible to know at this juncture what form that cooperation is taking, whether it'll last, and who is pushing whom into the fight, but all reports so far suggest that the UK and France are taking a leadership role. This strikes me as relevant for a couple of reasons: first, it of course helps defray accusations of quasi-imperial motivations like those that hounded the war in Iraq. Second, it forces the United States' hand a little bit. While it doesn't exactly sound like the US military was dragged into Libya, pressure from close allies (who, importantly, are themselves committing significant resources) changes the diplomatic calculus of military commitment. Compared to Iraq and Afghanistan, the question for American leaders seems less about whether a conflict is going to take place, and more about the role that Americans will play in a likely conflict. This reduced role does have some advantages: because it has less initial political investment in the war, and because it's more the cajoled than the cajoler, the US seems less likely to be left picking up the pieces alone, should things go badly south.
-The humanitarian concerns are immediate and pressing, not prospective. The pending slaughter seems to be a near-certainty, and is, at best, days away. Yes, as many, many people have pointed out, there's some hypocrisy in this justification, because Libya's hardly the only place in the world today where innocents are getting murdered by a dictator. But I don't think the situations are comparable; whatever is happening in Yemen, it hasn't deteriorated into civil war yet. By comparison, Libya is already ripping itself apart, and Qaddafi has more-or-less explicitly promised a massacre. Libya's rebels and protesters might not be better off after intervention, but it's also hard to imagine that they would be worse off.
-Oh, and there's Obama's promise to not put troops on the ground. Will he stick to it? I have no idea.
Obviously, there's a lot of reasons for skepticism here as well. Wars are expensive. Qaddafi may well try funding terror attacks against his persecutors. Even if we win, nobody knows what comes after Qaddafi. And we might not win.
There's also the one really big concern I have, which is that the mission will eventually require an actual invasion. The timeframe is just extremely problematic -- it seemed to me that the correct moment for action was before Qaddafi recaptured half the country. Air power and cruise missiles might have been able to stop his eastern advance but I don't understand how they're going to liberate occupied cities. The longer Qaddafi was locked in Tripoli while his government defected and the revolution fermented outside, the more likely it seemed he would be forced to flee, or that some frightened underling would just finish the job. But at this point, protecting innocents, the war's ostensible aim, seems to necessitate some sort of incursion into Libyan towns.
Like I said, I'm pretty ambivalent about the whole thing. And I'll fully admit to playing armchair general here. I don't know much about military conflict, nor Libya specifically, nor international diplomacy. On the other hand, if there is a lesson to be learned from the last few wars, it's that when it comes to wars, even the actual generals always get everything wrong. Ultimately, I guess I'm just left in the same place as everyone else: worried, but hoping for a quick end to the violence, a quick end for Qaddafi, and a better future in North Africa and the Middle East.