Chalk up another recruit for the idea of using mercenaries to stop the killing in Darfur: the liberal political philosopher Michael Walzer, author of Just and Unjust Wars.

In an essay in The New Republic, he notes that “neither the United Nations nor NATO has any intention of deploying a military force that would actually be capable of stopping the Darfur genocide.” So what’s the alternative? “Some of us might prefer something like the International Brigade that fought in Spain over a force of Blackwater mercenaries,” he writes, but failing another International Brigade, he endorses hiring firms like Blackwater (notwithstanding his aversion to security contractors in general).

This is a cause I’ve been pushing for a while (Walzer describes me in the article as “the leading neoconservative writer on military affairs”–I’m not sure whether that’s intended to be a compliment), and I’m happy to see Walzer lend his support. But the real challenge will be to get policymakers, whether at the UN or in the U.S., to go along, and so far there’s no sign of that. So the killing goes on.