There are 10 million refugees in the world -- or many, many more, depending on how you slice the statistics and whom you count. That's more than the populations of New Jersey and Maine combined fleeing war, torture, disaster, hunger; 10 million evicted from their homes, displaced, ethnically cleansed. Which means that we've seen these photos before. We've seen them, and we're familiar with the feelings -- the anger, pity, and guilt toward a world where horror is doled out wholesale and at random: Why should that five-year-old have been raped and not my daughter? Why must that family march through the desert for two weeks without food and not mine? Why must we keep seeing these images? We hate the questions because there are no answers. Except that there are. These wars, in East Africa or Southeast Asia or Central Europe, don't spring out of nowhere -- they proceed with cold, bloody logic from a handful of causes that aren't that hard to figure out. The war in Darfur, which has displaced at least 2 million and killed more than 70,000, is not a war over religion (victims and perpetrators are all Muslim) nor over race (while there is racist propaganda involved, decades of intermarriage have left Darfur's "Africans" and "Arabs" virtually indistinguishable), nor over "tribal animosities" (which do exist but didn't lead to war until two and a half years ago). It's a conflict that started, quite simply, because Sudan has a brutal, unpopular regime and rebel movements have sprung up in every corner of the country; because the civil war in the south (the one before Darfur, in which Muslim troops battled a Christian and animist uprising) was close to being settled, and so rebels in the west thought it a good moment to launch an offensive and the Sudanese government thought it a good strategy to let armed militias called janjaweed do its fighting. It's a war that is still going on because the government achieved what it wanted -- destruction of the villages that were feeding the opposition, confinement of the "displaced" in tightly controlled camps -- without paying much of a price. And it's going to stop the minute that strategy becomes politically untenable. International pressure -- specifically from American conservatives, who adopted the Christian cause in Sudan's south -- ended the country's other civil war; international pressure, from whomever chooses to step up, can end this one. We don't have to keep seeing these faces, the millions in Darfur, the millions more like them.