Rapprochement between Iran and the United States centers around the idea of shared threats. Iran, like the United States, has been forced to reckon with the rise of ISIS in Iraq and Syria. And both the U.S. and Iran are threatened by growing instability in Yemen. A working relationship over these issues might be the key to solving them, the thinking goes. But shared threats are not the same as shared interests.

Iran has an interest in maintaining Shia influence in Iraq, while the United States has an interest in stability. This distinction is important. Iranian-supported Shiite militias might be able to recapture Iraqi and Syrian cities, but taking back Sunni cities with a Shiite army won’t lead to stability. After Shiite militias retook the Iraqi city of Tikrit, for example, there were reports of executions and mutilations of the population.

This same distinction between common threats and interests applies to the conflict in Yemen as well. Iran and the United States are both threatened by growing instability and al Qaeda gains in Yemen, but interests don’t overlap. A Shiite government in Yemen would be a significant boon for the Iranians for geopolitical reasons — it provides easy access to Saudi Arabia, which lies on Yemen’s northern border. For the United States however, an Iranian-backed Houthi government would likely lead to further instability along sectarian lines, and prolonged civil war.

Simply put: Don’t expect a potential nuclear deal to be the start of a radical shift on other areas of Iranian foreign policy.