The idea that intervention in Libya was necessary to avert a genocidal bloodbath was always only worst-case speculation. The record of Muammar Qaddafi's regime suggests that a defeat of rebel forces in eastern Libya would have been followed by very harsh treatment of those who had taken up arms against the regime but not by atrocities inflicted more widely on a broader population. As an example of resort to military force based on a worst-case assumption of what the incumbent regime would do, accompanied by apparently insufficient thought about what would follow the initial intervention (anyone care to name another recent example?), the United States and the rest of the West fell into a trap of their own making.

Unlike the Bush administration's rhetoric about what Saddam Hussein “could” do with his presumed unconventional weapons, which was more a sales pitch than a genuine driver of the Iraq War, a humanitarian motive seems to have been an honest and important consideration for at least some in the Obama administration who deliberated on what to do about a rebellion-stricken Libya. But to follow a moral imperative in this way as a route to taking sides in someone else's civil war leads to an even bigger trap. The intervenor necessarily becomes associated with, but does not control, the favored side's subsequent behavior. If that side acts contrary to our moral principles, how do we act to stay consistent with those principles?

History offers numerous examples of conflicts in which what we in the West would regard as immoral behavior, even to the point of atrocity, was not the doing of only one side. And now in Libya we receive news of ugliness in the rebel-held eastern portion of the country, with the victims being persons having some association with the regime, even in as lowly a capacity as prison guard. There have been execution-style killings, with the bodies dropped in fields on the outskirts of Benghazi. Targets of other attacks have defected formally and openly to the rebel side, but having registered—per the instructions of rebel leaders—as former regime officials, they and their families still did not avoid becoming victims of violence.

What is happening in Benghazi is only a taste of what would happen if the rebellion were to succeed and the government-held eastern portion of the country—with far more people associated with the regime and liable to become targets of revenge—were to fall. Individual, uncontrolled, hatred-driven violence would be rampant, especially given the disorganization and indiscipline of a rebel movement whose self-declared leaders are still struggling to impose order and control in the portion of the country already lost to the regime. To be consistent with any moral principle that says one should do what one can to prevent widespread bloodshed, the West would have to become far more deeply involved in imposing order in post-Qaddafi Libya. The fact that the situation would be partly of the West's own making would make the moral obligation to do so all the more pointed.

What would have been the morally sound course before all of this started would have been to assess as well as possible all of the direct and indirect effects on the sum total of human suffering of each of the different possible courses of action the West might have taken. That may have been more difficult—intellectually, politically, and emotionally—than to say that one was intervening to stop an atrocity that was days away from happening. But it would have been right.