Read more of Slate's coverage of the Libya conflict.
The risks of arming and training Libyan forces, however, are also considerable. Civilians are not trained to fight overnight, so the NATO air operations will have to continue as the Libyan forces prepare to stand up. In the short term, of course, the violence would increase; essentially, NATO would be helping one side win a military victory, and that victory could be bloody. Even a bloody victory might avert greater suffering over time, but as casualties mount, opposition from skeptical NATO members like Turkey will grow. In the Arab world, latent suspicions about Western motives are likely to become manifest.
The rebels are also a political as well as a military question mark. Their leaders, their numbers, and their goals are not yet known—and, indeed, their ability to stick together and avoid infighting is also untested. Some rebel commanders admit that al-Qaida-linked fighters are within their ranks, admissions that seem to confirm the remarks of NATO's commander, Adm. James Stavridis, that the United States had "flickers" in its intelligence suggesting an al-Qaida presence. "The question we can't answer," Brookings analyst Bruce Riedel points out, "is, Are they 2 percent of the opposition? Are they 20 percent? Or are they 80 percent?" For NATO, keeping an arm's-length relationship with the rebels makes it hard to know the political dynamics within the opposition movement, let alone manipulate it.
From the rebel point of view, working with al-Qaida is logical. Both groups hate Qaddafi, and the jihadists are willing to put their own lives at risk, as opposed to helping out from 30,000 feet. As one Libyan commander put it, "members of al-Qaida are also good Muslims."
Cozying up to the rebels also risks tarring the United States and NATO with the misdeeds of these new allies. Reports that Qaddafi loyalists went house to house in contested areas, killing or arresting suspected oppositionists, appalled the world. The world should not be surprised if opposition forces pay Qaddafi back if they reconquer regime strongholds. Having suffered arrest, torture, and death at the regime's hands, oppositionists may not be forgiving if and when they take power.
Nor does the slippery slope necessarily end after rebels are armed and trained. As the United States has learned in Iraq and Afghanistan, training local forces is difficult and time-consuming at best, and wasteful and futile at worst. The rebels may remain ineffective militarily, or the pace of the killing may exceed the speed with which they can be trained. Yet if the United States goes farther down the road of involvement, and arms and trains the rebels, it becomes even harder to step back should further problems develop.
Getting closer to the opposition also increases U.S. and allied responsibility after Qaddafi falls. Having helped topple Qaddafi and bring the rebels to power, both the American people and the international community would think it callous if Washington simply washed its hands of Libya. It is hard to justify a humanitarian intervention if the replacement government is yet another dictatorship, but this result remains a possibility given the unclear character of the opposition forces. But since the U.S. strategic interest in Libya is limited at best, and given that there are no cultural ties that bind Americans to Libyans, preserving support for U.S. involvement will inevitably be difficult, and there will be little enthusiasm for post-Qaddafi meddling.
So while arming the rebels can help the United States and its allies solve the dilemma of how to make Qaddafi fall without deploying their own ground forces, it will not end, and in fact increases, the political burden the allies must bear.