The Ayatollah Ali Khamenei’s gains were more tangible than President Barack Obama’s. The Supreme Leader got significant sanctions relief for his ailing economy, the launch pad for Iran to become a more formidable Mideast power. Mr. Obama stretched Iran’s nuclear breakout time from a few months to over a year with strengthened inspection rights. But according to top administration officials, Mr. Obama has always been after something much bigger than capping Iran’s nuclear program, and he got it—the strategic opportunity to begin converting Iran from foe to “friend.”

Iranian negotiators understood well what’s been driving the U.S. president, and they have used the prospect of becoming “a friend” as their best bargaining card. For over a year now in small private conversations and strolls, they have been painting rosy pictures of Iranian-American cooperation.

The Iranian list of possibilities goes to most of Washington’s principal worries about the broad Middle East. They would step up their fighting alongside Iraqi troops to combat the so-called Islamic State (ISIS or ISIL) in central Iraq. And they would do much more in Syria to go after the headquarters and main forces that ISIS has there. They spoke of finding “solutions” to the civil war in Yemen between Sunnis and Iran-backed Shiites. They raised hopes of forging better relations with America’s “partners” in the Gulf. They pressed the idea of  renewing the cooperation they once had with the U.S. fighting the Taliban at the beginning of the Afghan war.