Scratch the surface of most of the world’s armed conflicts and you won’t see an ideological struggle or deep-seated ethnic or religious hatred that has erupted in a war of all against all. Rather, what you’ll find is a collection of thugs for hire, some in uniforms and some not, who are taking advantage of the chaos of war to prey on the weak. Sometimes this involves stealing oil or diamonds, or sexual brutality. But it’s pretty rare that it involves some larger design. True, the hooligans who take part in these orgies of destruction will often claim loyalty to some larger cause. They’re usually lying. The only heroes you’ll find in these wars are the people fighting for their lives and their loved ones.

The war that is now unfolding in Iraq is something different, and something much scarier. The Islamic State of Iraq and Syria steals with the best of them, and I don’t doubt that some of the fighters who’ve attached themselves to its cause are thrill-seeking psychopaths like those you’ll find in any lawless hellhole. On the whole, however, you get the impression that its fighters aren’t killing for fun and profit, and they’re certainly not killing to protect themselves from other crazies. Instead, they are killing because they are utopians. They want to live in a world that is quite literally cleansed of those who do not share their deranged beliefs, and by killing Yazidis and Christians and members of other religious minorities, they believe that they are serving a noble and just cause. The Taliban are awful, but given their willingness to cut deals with the Afghan government and the United States and its allies, they aren’t quite so insane. Even al-Qaida is more tolerant of religious minorities than the lunatics of ISIS. Now, with hundreds of millions of dollars worth of stolen loot, ISIS is on the march, closing in on stranded pockets of women and men they see as pagans and slowly starving them to death. The Kurdish peshmerga, the only Iraqi fighting force capable of holding ISIS at bay, has put up a brave resistance, yet they are starting to buckle.

And now, without a moment to spare, President Obama has decided to do something. For months, the president has resisted committing U.S. military forces to the fight against ISIS. But ISIS’s campaign of extermination against Iraq’s religious minorities has stirred him to action. In a nationally televised address on Thursday night, the president announced that he had authorized a limited bombing campaign against ISIS as well as a humanitarian effort on behalf of the stranded Yazidis.