At first glance, the framework nuclear deal reached between Iran and world powers was more comprehensive and detailed than expected.
But there is much to sort out before a final agreement can be reached. Both Tehran and Washington now face the difficult task of selling the terms at home and to allies abroad, and some of the sticking points are serious enough that they could prevent the deal from being signed by the June 30 deadline.
The critics wasted little time voicing their opinions of the framework agreement. Iranian hard-liners portrayed the deal as a bargain for the West and a disaster for Iran. Israel called the deal dangerous, saying it left much of Tehran's nuclear infrastructure intact. Some U.S. senators said the deal did not go far enough.
Lifting Of Sanctions
The tricky issue of when crippling Western sanctions on Iran will be lifted remains unresolved.
Iran sought the immediate lifting of all UN, U.S., and EU sanctions. But according to the public document released by the United States listing both sides' commitments, there would only be a gradual easing of the sanctions.
The U.S. fact sheet said Iran will be granted relief from sanctions if it "verifiably abides by its commitments." That would be determined by the UN's nuclear watchdog, the International Atomic Energy Agency.
Following the deal, Iranian Foreign Minister Mohammad Javad Zarif questioned the speed of a U.S. sanctions drawdown.
"The sanctions part of the deal is vague and it's more open to interpretation", says Ali Vaez, a senior Iran analyst at the International Crisis Group. "The exact mechanisms of sanctions relief remain unclear, so it makes the task of defending the deal back home more difficult."
Iranian hard-liners have said they will oppose any deal that would diminish Iran's nuclear enrichment program that would leave sanctions intact.
Research And Development
One of the biggest sticking points in the talks was over Tehran's demand that it be allowed to pursue the research and development of advanced centrifuges, machines that can spin uranium gas to levels high enough to be used in nuclear warheads.
Tehran insisted that it be allowed to continue such research and development, but the idea ran into opposition from Western powers intent on reducing Iran's "breakout time" -- the time needed for Iran to enrich enough uranium for a nuclear weapon.
In the end, according to the U.S. fact sheet, it was agreed that Iran would be able to conduct "limited research and development" into the centrifuges "according to a schedule and parameters which have been agreed to" by the sides. The specifics remain unknown.
Critics of the deal were quick to home in on the issue. "It leaves Iran with thousands of centrifuges to continue to enrich uranium, and allows Iran to continue research and development on better and faster centrifuges," Israeli government spokesman Mark Regev said on April 3.
As part of the deal, Iran agreed to stop enrichment at the Fordow nuclear facility, changing it to a nuclear research center.
Conservative Iranian analyst Mahdi Mohammad was quoted by Iranian media outlets as saying that a "disaster happened in Fordow."
Hard-line conservatives in Iran had said they would oppose any deal that would diminish Iran's nuclear program. Supreme Leader Ayatollah Ali Khamenei even named the protection of Fordow among his 11 red lines issued in October.
Under the framework deal, Iran's unfinished Arak reactor will not produce weapons-grade plutonium. The redesign of Arak will also have to be detailed in any final deal.
"If the signal out of the Friday Prayers is any indication, the supreme leader has basically said we accept the framework," says Scott Lucas, an Iran specialist at Birmingham University in Britain and editor of the EA World View website. "That means Iran's hard-liners are going to have to count on something going wrong over the next three months to be able to have any traction to take down a deal."
Vaez says Iran's conservatives will find it hard to oppose the deal. "Now we are at a place where Iran's right to enrichment has been explicitly recognized and it has the possibility of shedding its status as a pariah state and will able to economically benefit from sanctions relief," he says.
Another unresolved issue is the fate of Iran's stockpile of low-enriched uranium.
The U.S. fact sheet says Iran has agreed to "reduce" its current stockpile of 10,000 kilograms to 300 kilograms. But it does not say how Tehran should do this -- whether by shipping the uranium to another country, such as Russia, or diluting it inside Iran.
Western powers had expected Iran to export its uranium out of the country so it could not be used for military use. But late in the negotiations in the Swiss city of Lausanne, Iranian negotiators toughened their stance, insisting Iran would dilute the uranium itself to a purity that would make it impossible to build a nuclear weapon.
Critics of the deal point to the risk that the diluted uranium could still be converted for weapons use. Ray Takeyh, senior fellow at the Council of Foreign Relations, wrote in The Washington Post on April 2 that under the framework deal, "Iran would maintain a substantial enrichment capacity. Iran's massive stockpile of enriched uranium would not be shipped to Russia for reprocessing but would be diluted somehow."
"The deal is mainly Iran making concessions," Lucas says. "The longer the U.S. can say the Iranians are cutting their nuclear program back the more it eases the situation with Congress."