I'm not much of a Realist when it comes to foreign policy. That's not to say I don't care about protecting America's interests abroad, just that it isn't the overriding concern. The sort of Cold War mentality where we prop up evil dictatorships to keep them out of the Soviet column is abhorrent to me. So, if someone says "we need to intervene in Sudan because their oil resources are a vital strategic interest," I'm skeptical. But if they say "Sudan's in the midst of a genocide--we need to save lives!" I start paying closer attention.
But not everyone is like me. And that's why this New Republic article laying out the Realist case for a Darfur intervention is so important. It's clearly written, compelling, and urgent. Everyone should read it.
The gist of the argument is that we need to check China's influence in Africa. Basically, every time we withhold economic or political support to an African regime because they're hacking the limbs off their citizens (or whatever), China rushes to fill the gap. So when the US delayed giving Nigeria the arms shipment they wanted, they just ran to China, who said "sure thing!" China offers economic, military, and political assistance to all comers, and (and here's the important part), a shield via its security council veto against meaningful international sanction.
This is where Sudan comes in. Sudan is one of China's biggest client states. And, by committing genocide, Sudan is also the biggest human rights violator in the region. If the US doesn't intervene in Darfur, the message is that China's influence can prevent meaningful sanction over literally any governmental policy. And we, for obvious reasons, don't want that: it would give a blank check to any machete-wielding militia with government support, it would make human rights in the region a dead letter, and it would eliminate any hope the US had of competing with China for regional influence (after all, why bother abiding by pesky American rights standards when China will give you the same support for free?).
I buy the analysis. But since I'd be willing to intervene even without that argument, I'm not the important guy here. It's on the rest of you now. Go forth, and read.