In fact, we have seen atrocities much worse than those in Syria very recently, in Iraq under U.S. occupation only few years ago. From 2003 to 2012, despite there being as many as 180,000 American and allied troops in Iraq, somewhere between 150,000 and 300,000 Iraqi civilians died and about 1.5 million fled the country. Jihadi groups flourished in Iraq, and al-Qaeda had a huge presence there. The U.S. was about as actively engaged in Iraq as is possible, and yet more terrible things happened there than in Syria. Why?

The point here is not to make comparisons among atrocities. The situation in Syria is much like that in Iraq--and bears little resemblance to that in Libya--so we can learn a lot from our experience there. Joshua Landis, the leading scholar on Syria, points out that it is the last of the three countries of the Levant where minority regimes have been challenged by the majority. In Lebanon, the Christian elite were displaced through a bloody civil war that started in the 1970s and lasted 15 years. In Iraq in 2003, the U.S. military quickly displaced the Sunni elite, handing the country over to the Shi'ites--but the Sunnis have fought back ferociously for almost a decade. Sectarian killings persist in Iraq to this day.

Syria is following a similar pattern. the country has a Sunni majority. The regime is Alawite, a Shi'ite subsect that makes up 12% of the population, but it also draws some support from other minorities--Druze, Armenians and others--who worry about their fate in a majoritarian Syria. These fears might be justified. Consider what has happened to the Christians of Iraq. There were as many as 1.4 million of them before the Iraq war. There are now about 500,000, and many of their churches have been destroyed. Christian life in Iraq, which has survived since the days of the Bible, is in real danger of being extinguished by the current regime in Baghdad.

All the features of Syria's civil war that are supposedly the result of U.S. nonintervention also appeared in Iraq despite America's massive intervention there. In Iraq under U.S. occupation, many Sunni groups banded together with jihadi forces from the outside; some even broke bread with al-Qaeda. Shi'ite militias got support from Iran. Both sides employed tactics that were brutal beyond belief--putting electric drills through people's heads, burning others alive and dumping still breathing victims into mass graves.

These struggles get vicious for a reason: the stakes are very high. The minority regime fights to the end because it fears for its life once out of power. The Sunnis of Iraq fought--even against the mighty American military--because they knew that life under the Shi'ites would be ugly, as it has proved to be. The Alawites in Syria will fight even harder because they are a smaller minority and have further to fall.

Would U.S. intervention--no-fly zones, arms, aid to the opposition forces--make things better? It depends on what one means by better. It would certainly intensify the civil war. It would also make the regime of Bashar Assad more desperate. Perhaps Assad has already used chemical weapons; with his back against the wall, he might use them on a larger scale. As for external instability, Landis points out that if U.S. intervention tipped the balance against the Alawites, they might flee Syria into Lebanon, destabilizing that country for decades. Again, this pattern is not unprecedented. Large numbers on the losing side have fled wars in the Middle East, from Palestinians in 1948 to Iraq's Sunnis in the past decade.

If the objective is actually to reduce the atrocities and minimize potential instability, the key will be a political settlement that gives each side an assurance that it has a place in the new Syria. That was never achieved in Iraq, which is why, despite U.S. troops and arms and influence, the situation turned into a violent free-for-all. If some kind of political pact can be reached, there's hope for Syria. If it cannot, U.S. assistance to the rebels or even direct military intervention won't change much: Syria will follow the pattern of Lebanon and Iraq--a long, bloody civil war. And America will be in the middle of it.