Advocates of a Libyan intervention don’t seem to have internalized these lessons. They have rallied around a no-flight zone as their Plan A for toppling Qaddafi, but most military analysts seem to think that it will fail to do the job, and there’s no consensus on Plan B. Would we escalate to air strikes? Arm the rebels? Sit back and let Qaddafi claim to have outlasted us?

If we did supply the rebels, who exactly would be receiving our money and munitions? Libya’s internal politics are opaque, to put it mildly. But here’s one disquieting data point, courtesy of the Center for a New American Security’s Andrew Exum: Eastern Libya, the locus of the rebellion, sent more foreign fighters per capita to join the Iraqi insurgency than any other region in the Arab world.

And if the civil war dragged on, what then? Twice in the last two decades, in Iraq and the former Yugoslavia, the United States has helped impose a no-flight zone. In both cases, it was just a stepping-stone to further escalation: bombing campaigns, invasion, occupation and nation-building.