The critical question today is whether the current civil war could spread beyond Iraq’s borders, engulfing its neighbors or sparking a regional war.
Iraq, after all, is not the only Middle Eastern state to have a mixed population of Sunnis, Shiites, and other religious groups. There are substantial but not overwhelming numbers of Shiites in Bahrain, Kuwait, Lebanon, Saudi Arabia, Syria, Turkey, and Yemen, to say nothing of Afghanistan and Azerbaijan. Even predominantly Shia Iran has its Sunni minority, among them the persecuted Ahwazi Arabs, who live in the strategically vital southwestern province of Khuzestan.
...Only in our time, then, has the Middle East reached the political stage that Central and Eastern Europe reached after the First World War. Only now are countries like Iraq and Lebanon experimenting with democracy. The lesson of European history is that this experiment is a highly dangerous one, particularly at times of economic volatility and chronic insecurity, and particularly where tribes and peoples are mixed up geographically, both within and across borders. The minorities fear—with good reason—the tyranny of the majorities. People vote their ethnicity, not their pocketbook or ideology. And even before the votes are counted, the shooting begins.
Of course, it wasn't merely ethnic tension that helped to fan the flames of war (nor does Ferguson say as much, to be clear.) There were numrous other causes, including fervant nationalism (related to the ethnic divisons), a belief in the superiority of offense, each sides mis-readings of each other's motives, lack of control over military planning, and so on. Unfortunately, as Ferguson also point out, ethnic tension has been a highly aggravating factor in very recent conflicts, such as Rwanda and Bosnia. And like in Rwanda and Bosnia, there are those who see opportunity in ethnic conflict. Here's Jeb from Foreign Policy Watch:
This divide is becoming more and more acute, many analysts are now saying, as violent news from Iraq has caused passionate anti-Shia sentiments to sweep through the region. This phenomenon has been further encouraged by Sunni Arab governments who hope to undermine the increasing influence of Iran by promoting anti-Shia attitudes.Of course, it is far from certain that such tensions could lead to conflict between other Middle Eastern nations beyond Iraq. As with the situation that existed pre-WWI, other factors are in play, including some power politics being conducted by Arab governments hostile (and not that hostile-see Syria) to Iran. Still, it is not at all encouraging that ethnic tensions are on the rise. That Iraq could serve as the instigator of regional war in the Middle East, a Gavrilo Princip writ large, is a horrifying possibility I don't think was predicted by even the staunchest of the invasion critics, myself included.
...This new divide between Shiites and Sunnis has actually become quite severe. As [Marc] Lynch has said, and other analysts have also pointed out, anti-Shia sentiment has been on the rise primarily because of events in Iraq. While I wrote in my earlier post that I believed this to largely be a (Sunni) government-encouraged phenomenon, I seem to have been wrong on this point. Instead, more knowledgeable analysts suggest that it is the carnage in Iraq that is causing this new sectarianism. The brutal Shiite violence against Sunnis has resulted in anger towards the region's Shiite population and, as an extension of this, undermined Iran's popularity, because of their backing for these Shiite groups.