Is the United States going to war with Russia? It’s a fair concern in light of recent events. But a better question might be this: Is the US sliding into a war with Iran?

What prompts the talk of war is an escalation of conflict above Syria. After a US jet shot down a Syrian fighter plane, on Monday Russia sternly warned that it would shoot down any aircraft flying over western Syria.

But on Tuesday, a more telling event occurred. The US shot down an Iranian-made drone. It was the fifth such incident in the past six months. The US says it’s protecting rebels (and American advisers) who are battling Islamic State (ISIS) near the Syrian-Iraqi border. That appears to be true and we wrote about that two weeks ago.

Iran is fighting ISIS, too. But there’s a bigger picture – and pattern – emerging. As ISIS retreats, the US, Saudi Arabia, and Israel see Iran’s influence expanding. They fear an emerging “Shiite crescent” of control from Iran to Lebanon.

The Pentagon says it isn’t picking a fight with Russia or Syrian President Bashar al-Assad’s forces. But given Iran’s rising military reach, any path to progress in the region will likely go through Tehran.