Both sides misjudged Obama, who has proceeded to chart a course with Iran that is neither fully conciliatory nor bellicose. Over the previous few years, the president has used his office to repeatedly extend offers of rapprochement to Iranian leaders. And when those attempts have been rejected — firmly — he has used diplomacy to build an unprecedented wall of international opposition to Iran’s nuclear program and preside over the imposition of the harshest economic sanctions in the country’s history.

At the same time, the Obama White House has proven to be no more successful than its predecessors at halting Iran’s nuclear advance, the singular goal that has driven U.S. policy on Iran since the George H.W. Bush administration. Indeed, Iran’s rate of production of enriched uranium has nearly tripled since Obama took office, while hopes that the president can deliver a solution to the crisis have faded, even among his former admirers in Iran…

For now, the Obama administration is seeking to further increase the pain for Iran, responding in part to pressure from Israel and from Congress, which has consistently urged harsher measures, including some that U.S. officials fear could hurt allies as well as Iranians. Although sanctions rarely work, independent analysts say a groundswell of economic unrest could force the regime to make concessions if it sees its survival at risk.

“Two clocks are now running: a nuclear clock and regime-change clock,” said Clifford Kupchan, a former State Department official who now serves as a private consultant on the Middle East. “Sanctions have put a big hole in the revenue side of Iran’s budget, but the leadership doesn’t yet know that it’s on a cliff.”