[T]he notion that "whenever humanitarian emergencies break out, we do nothing to stop them" is incorrect. During the Clinton administration, the United States intervened to stop the mass slaughter of Bosnians and then Kosovars. It didn't work perfectly, but it worked, and it would have worked better if we had intervened earlier.
I'd also point out that the notion that the United States can't intervene militarily without U.N. Security Council authorization is not a historical norm that existed before the Bush administration smashed it. In fact it's never existed at all. ... No government in American history has ever committed itself to gaining U.N. permission before using non-defensive force. ... Previous governments did pay more attention to international opinion than the Bush administration has, but none of them granted it veto power. The Clinton administration's motto in this regard was "Multilateral when we can, unilateral when we must."
Chait's post misses the point. I don't think Yglesias nor myself would argue that the US must get UN Security Council authorization every time, no exceptions. Yglesias himself says that the Kosovo action was justified, and I tend to agree.
The issue is not whether we can take action, but whether we should. If you look at the world's worst humanitarian emergencies and ethnic wars, basically none of them would be approved by the arrival of a multinational coalition of the willing. Many of them would be made much worse off, with massive humanitarian calamity and social collapse. The problem is less about whether we needed the Security Council to okay the US taking action in Iraq and more about whether we should have at all. We shouldn't have. It was a bad idea. By the same token, US unilateral or coalition-based military invasions, occupations or strikes against bad actors in Burma, Iran, North Korea, Somalia, Sudan, Congo, or Zimbabwe are all terrible ideas. It doesn't matter whether the Council would give the okay to any of them. The policy itself would lead to a bad outcome.
Not that that's something I'd expect anyone at The New Republic to understand, given their general foreign policy stance.
One more point: Chait attacks people who think that military interventions are generally a bad idea by calling them wimps on Bosnia:
There is a school of thought which holds that U.S. intevention in the Balkans was a pretext to kill people rather than a genuine effort to stop genocide. But this school is mostly associated with extreme Serbian nationalism. I'm surprised to see it propounded by an organ of mainstream American liberalism.
The problem with this was that the case of Bosnia was an international incident, where sovereignty was violated by one ethnic nation (Serbia) trying to carve out a sister nation of the same ethnic group (Republika Srbska) in a neighboring nation (Bosnia) through ethnic cleansing. This absolutely warranted a military response and, belatedly, it got one. But how Chait would apply this to proxy wars in Somalia and DR Congo, or internal strife in Zimbabwe or Burma, is a complete mystery to me.