“Both the chaos in Afghanistan and in Iraq could have been avoided had Washington recognized the stabilizing role Iran can play if it isn’t treated as an outcast,” Trita Parsi, president of the National Iranian American Council, wrote recently.

Yet for all the possible benefits to Iran of cooperation with the West, its rulers are also anxious not to be seen as an ally of the United States, and especially not of Washington’s protege Israel, against Sunnis who outnumber Shi’ites two to one across the Middle East. More mixed messages can be expected.