“So many proponents of the deal have argued that there will be a spillover effect — that if we can get this deal then we would be likely to alter Iran’s trajectory on its regional approach as well as its domestic policies,” says Suzanne Maloney, an Iran expert at the Brookings Institution.

“I don’t tend to think that’s the case. There are plenty of reasons to question how this deal is going to play out with regard to Iran on the other issues of concern to the U.S.”

For instance, some Iran watchers fear that if Iran’s Supreme Leader, Ali Khamenei, accedes to pressure from moderates and business leaders to approve the nuclear deal, he may try to appease hardliners and demonstrate his resolve by opposing the U.S. more strenuously in other ways…

More doubtful is Kerry’s predecessor, Hillary Clinton, who evinces little hope that Iranian behavior will change anytime soon. “[E]ven if the nuclear issue was eventually settled by an enforceable agreement, Iran’s support for terrorism and its aggressive behavior in the region would remain a threat” to the U.S. and its allies, Clinton wrote in her 2014 memoir, adding of the nuclear diplomacy itself that “I had seen too many false hopes dashed over the years [by Iran] to allow myself to get too optimistic now.”