A failure to successfully translate this interim deal into an end to Iran’s suspected nuclear weapons program would also be damaging for President Barack Obama. But he knows that he will not be able to win congressional support for a long-term deal unless it is very specific and buttoned-down regarding eliminating the threat of Iran’s rollout of a bomb in the near term. At this moment, the president, the secretary of state, and their teams are seen as having taken a risky tack, and if it fails, history will forever mark them as appeasers, naifs who were played by Tehran. The only way to avoid a damaging outcome is a long-term deal that works in the eyes of its critics.
It should also be noted that the Iran negotiations, coming as they do at the same time as the Syria negotiations, contain other risks that cut both ways for the United States, Iran, and the other parties to both sets of negotiations. If Iran appears to be acting in bad faith or if this deal goes sour, the international community will have the option of punishing Iran’s leaders by withdrawing support for their desired outcome in the Syria talks — either keeping their long-term ally, President Bashar al-Assad, in place or accepting a successor regime that preserves their interests and influence in that country. On the other hand, if Iran actually makes real progress on the nuclear deal, the country may be rewarded at the Syria negotiating table. Of course, none of this will be explicit or even discussed. But it is the nature of diplomacy to link such things if they are proceeding in parallel.