In the intervening period, several factors moved Iran toward the bargaining table. One factor was the galvanization of the international community once President Obama’s offers to engage made Iran’s arguments about U.S. intransigence look shrill. Moreover, tumbling oil prices have put a significant strain on Iran’s fiscal health, especially its domestic subsidies that are critical to national tranquility. These factors led to an enhanced sanctions regime, both in terms of scope and effectiveness. Another factor occurred at Iran’s ballot box. President Rouhani succeeded President Ahmadinejad in 2013 and, with it, Iranian tone shifted in constructive ways.
While there have been important benefits to negotiations, it has also come with three chief costs. First, the negotiations took time, which Iran could use to further its drive toward nuclear weapon capability. This concern seems to assume some other decisive actions (including military ones) could have eliminated the Iranian nuclear program in the absence of the diplomatic effort, but it is difficult to conceive what would have been reliably effective.