The U.S. allows Tehran to keep its nuclear program with the secret hope that America's foe will become a friend.

Both Iran and the United States essentially got what they wanted from the 159-page nuclear deal agreed Tuesday in Vienna.

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.