“The interests that have determined US policy toward Iran for decades – accommodating the interests of Israel and Saudi Arabia and the usefulness of having Iran as an adversary in justifying military deployments, missile defense programs and large-scale arms sales to the Gulf – remain in place,” he added.

The talks in Vienna between Iran on one side and Russia, China, France, the US and the EU plus Germany on the other are running into serious difficulties as the sides are trying to pass on to a practical stage to elaborate a draft of a comprehensive agreement on Iran’s nuclear program.

“The problem in this crucial stage of beginning the actual drafting of the agreement is that the United States is taking a position on the enrichment capabilities Iran would be allowed that is completely unacceptable to Iran,” Porter told RIA Novosti. “It is demanding that it be limited to a small fraction of what it now has on the basis of a ‘breakout’ scenario that is quite implausible.”

At the same time, worries about slow progress could be over exaggerated, and Anoush Ehteshami, a professor of International Relations at Durham University said that in the context of the negotiations that started in 2003 and yielded no results for a decade, the recent progress has been remarkable.

Last November, Iran and the P5+1 agreed in Geneva on the temporary limiting of Iran’s nuclear program in exchange for a partial halt of US and EU sanctions against Iran.

“Now they start with the final stage measures. So progress has been remarkable and the conservatives in both Tehran and Washington managed to keep quiet and let this process proceed between diplomats,” Ehteshami told RIA Novosti.

At the same time, he noted that both Washington and Tehran have a common goal “of persuading their own domestic constituencies that what they are doing is good for their countries.”

“Iran wants to persuade its conservatives that it is not abandoning its nuclear program and Obama has to persuade the Congress that what he is doing in the negotiations is that he is making sure Iran doesn’t become a nuclear state. They both understand what needs to happen and to be done,” Ehteshami said.

In the US, Congress is skeptical about Iran’s program, and the sides also need to discuss the issues of regional security. But neither Israel – Washington’s main ally in the region – nor Saudi Arabia is ready for such an eventuality.

“Washington would like a deal that it can sell easily to a Congress dominated by pro-Israel interests. But it now appears to be unready to agree to a comprehensive agreement that would be attacked by those interests,” Gareth Porter said.