So, President Obama has announced that the US is delivering air-dropped humanitarian aid to refugees in northern Iraq, and that he has authorised air strikes to prevent a genocide.

As a rule, I tend to side with 'defensive realists' such as Stephen Walt on these issues. As Walt argued yesterday:

Some will argue that we have a moral responsibility to try to end the obvious suffering in different places, and a strategic imperative to eradicate terrorists and prevent the spread of WMD. These are laudable goals, but if the history of the past twenty years teaches us anything, it is that forceful American interference of this sort just makes these problems worse. The Islamic State wouldn't exist if the neocons hadn't led us blindly into Iraq, and Iran would have less reason to contemplate getting nuclear weapons if it hadn't watched the United States throw its weight around in the region and threaten it directly with regime change...

...this argument would not preclude limited U.S. action for purely humanitarian purposes -- such as humanitarian airdrops for the beleaguered religious minorities now threatened with starvation in Iraq. That's not "deep engagement"; that's merely trying to help people threatened with imminent death. But I would not send U.S. forces -- including drones or aircraft -- out to win a battle that the Iraqi government or the Kurds cannot win for themselves. The United States spent the better part of a decade chasing that elusive Grail, and the end result was precisely the sort of chaos and sectarian rivalry that has produced this latest crisis.

Yet if Obama's description of the situation is accurate, the distinction between military and humanitarian action is far from clear cut. Obama opened his statement by saying the refugees stranded on a mountain in northern Iraq faced 'certain death' (he also used the word 'genocide') from ISIS. If it's acceptable to help these people by feeding and sheltering them, I see no obvious moral barrier to using proportionate and discriminating force to protect them too. In fact, if there is a moral imperative to help the refugees with aid, it would be somewhat obtuse to refuse them other kinds of assistance when it is available.

Of course, this moral logic needs to be bounded by practical reasoning. Will force actually work, or will it make things worse? That is Walt's concern, and I share it. The use of force therefore needs to be severely limited, but it should not be ruled out entirely. I think the tone of Obama's statement, and his reluctance to use force in Syria, suggest this is his instinct too.

BTW, if you're looking for background on the Yazidi, the religious group ISIS is evidently trying to exterminate, look here. (H/t Browser.)