Megan McArdle, based on a talk by Stephen Carter, comes to the view that "that when Americans say 'someone should do something' to stop a conflict somewhere, this is almost tantamount to saying 'we should do something', because at a most generous estimate, there are four military forces in the world capable of deploying into a conflict zone and shutting down the war: America, Britain, Australia, and Israel . . . when we decide not to intervene, we are making a decision that no one should act to halt the conflict."

There's some truth to that, but I think the perspective needs some nuance. It's true that very few countries can, acting alone, intervene in meaningful ways in civil conflicts. But that's not to say that those countries can't contribute constructively to military undertakings. It's to say that they can only contribute helpfully if the United States is also contributing and is thus able to help out with some of the logistical elements and/or perhaps do the pointiest fighting. But as we're seeing right now in Iraq, even the enormous US military establishment faces meaningful manpower constraints relative to the task of stabilizing medium-sized areas so when you're thinking about the feasibility of doing something or other, whether or not other countries are pitching in makes a real difference.

Then beyond that there's the question of politics. The African Union doesn't have a ton of military heft behind it. But there's a huge difference in terms of politics and legitimacy between an operation in Africa led by a western power and supported by AU member states operating joint blessings from the AU and the UN Security Council and an operation in Africa where a western power unilaterally intervenes.

Last, whenever people make these capacities-based arguments you do need to ask as a followup whether this just happens to be an argument they're wielding on behalf of a policy of aggressive unilateralism or whether they're also trying to advocate for steps to ameliorate the capabilities issue. Should there be a UN Standing Force? I think perhaps there should. Was the Center for American Progress correct to recommend that the 2006 QDR involve helping the African Union to build capacity "to solve regional con´Čéicts, thus reducing the need to deploy U.S. forces"? I think they were.

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