Some of my fence-sitting friends tell me my initial thoughts about the Libyan war were far too pessimistic. Gaddafi doesn’t really have any support, they say — never mind all evidence to the contrary — the U.S. will take a back seat to France, Britain, and maybe the Arabs in the war; and our involvement won’t escalate into anything more than the no-fly zone and a bit of bombing.

Just as in the run-up to the Iraq War I could see no realistic scenario in which Saddam Hussein could pose a threat to the United States, try as I might I cannot envision how my critics’ hopes can be justified. What they, and some of the outright hawks, are saying is that as long as Gaddafi is deprived of his jets, the rebels will be able to beat him swiftly. A humanitarian catastrophe will be averted, and Libya will have liberated itself, with just the slightest tip of the scales from outsiders.

Let’s look at what’s actually likely to happen. Gaddafi’s ground forces are better trained and equipped than the rebels. Gaddafi has plenty of money to hire additional mercenaries to augment his force further. Even with his air force grounded and Western arms going to the rebels, the advantage appears to be very much Gaddafi’s, at least in the immediate term.

The no-fly zone might be able to check his advance — right now it’s not clear that even that much is true. But if the no-fly zone can do for Benghazi what a no-fly zone did for Iraq’s Kurds in the 1990s, what happens next? The no-fly zones over Iraq did not loosen Saddam Hussein’s grip on power. This outcome amounts to a stalemate, one that must be continually enforced by outside powers. Sanctions are usually part of this policy mix as well, and those will impose a terrible cost on the Libyan people, as they did on the people of Iraq 20 years before. And don’t forget how the Iraqi no-fly situation was finally resolved: with an American invasion. Is it worth repeating all of that?

But perhaps the no-fly zone and Western arms will enable the rebels to push back against Gaddafi more effectively than the Kurds and Shi’ites were able to resist Saddam. In this scenario, the result is a full-blown civil war. And here humanitarian interventionists are faced with a question they dare not even ask, let alone answer: namely, what is more lethal for civilians, a brutal Gaddafi-style dictatorship or a pitched civil war? There is an empirical answer to this question.

There is absolutely nothing to suggest that the rebels, aided by a no-fly zone and additional weapons, will be able to depose Gaddafi swiftly. It could happen by a stroke of luck — Gaddafi could be struck by lightning tomorrow — but the balance of forces is against it. A prolonged civil war would be a catastrophe for civilians, and an embarrassment for the West. I don’t think such a situation would be allowed to continue long.

Which leads to the final scenario. Gaddafi can be deposed quickly, but only by outside forces, not by the rebels. Indeed, considering the arguments the interventionists have so far made, why would they be against sending ground troops? By any reasonable measure, Gaddafi’s forces can be expected to be even less effective against Western soldiers than Saddam Hussein’s were eight years ago. Why wait a few months and allow the humanitarian situation to deteriorate? Why not end Gaddafi’s reign of terror right now (or at least as soon as the logistics are in place)?

A stalemate enforced by a perpetual no-fly zone and sanctions will not satisfy anyone. A civil war fueled by Western arms and limited intervention would be counterproductive for humanitarian concerns. The logic of intervention points to sending ground forces, and the sooner the better. The involvement of Western ground forces, of course, will entail occupation and nation-building in the aftermath of Gaddafi’s defeat, with all the attendant collateral damage and strategic baggage I have warned about.

The interventionists want to compare a Libyan war to the war against Serbia. One of my fence-sitting friends, who isn’t actually an interventionist but apparently wants to seem even-handed and open-minded, says Gaddafi doesn’t have the support Slobodan Milosevic had. Really? I don’t know how anyone in the West could be sure about that. It seems to me that however much Libyans may hate Gaddafi, the old colonel has far more resolve and resilience than Milosevic ever displayed. Gaddafi has been a target of Western airpower before; he also lost a decade-long war with Chad. He’s faced internal opposition before. And far from striking fear into the hearts of dictators everywhere, the spectacle of a pathetic Milosevic in the dock at the Hague, dying of a heart attack while on trial, gives the Gaddafis of the world all the more reason to fight to the end. Wouldn’t Gaddafi rather die with his boots on? Wouldn’t you?

Maybe the interventionists will get really lucky, Gaddafi’s forces will just melt away, and the rebels will take Tripoli within two weeks. But nothing we’ve seen so far in this uprising, and nothing in Gaddafi’s 42 years of clinging to power, suggests that will happen.