By Ann Curry, NBC News National and International Correspondent
GENEVA -- Secretary of State John Kerry and leaders from five other world powers early Sunday reached a nuclear deal with Iran, following intense negotiations that took place over several days in Geneva.
The deal represents a historic breakthrough in the world's decade-long nuclear standoff with Iran, and in the 35-year-long diplomatic freeze between Iran and the United States.
The deal was struck with astonishing speed given the history of failed negotiations, coming in just the third round of talks over less than two months. The breakthrough also comes less than three months after Iran's new President Hassan Rouhani promised, in an interview with NBC News, to dramatically alter Iran’s relationship with the world.
EU High Representative for Foreign Affairs and Security Policy Catherine Ashton said the agreement was an important step toward reaching a long-term comprehensive solution. She added that the deal shows participants' "mutual respect and determination to find a way forward which is beneficial to all.”
At a news conference, Kerry said the agreement could not have been reached without the Iranians' decision to come to the negotiating table. He said the next phase of negotiations – while even more difficult – will also be more consequential, and he added: "If this first step leads to what is our ultimate goal – which is a comprehensive agreement – that will make the world safer.”
Iran and six of the world's powers – the United States, France, Britain, Germany, China and Russia – agreed on a "first step deal” that is meant to limit advancements in Iran's nuclear program in exchange for easing some of the economic sanctions that have deeply hurt Iran's economy.
According to the White House, the deal stipulates that Iran will commit to halt uranium enrichment above 5 percent and also to neutralize its stockpile of near-20 percent enriched uranium. The Islamic Republic has also committed to halt progress on its enrichment capacity. Iran will also halt work at its plutonium reactor and provide access to nuclear inspectors.
These steps, President Barack Obama said late Saturday, will "cut off Iran’s most likely paths to a bomb.”
In exchange, the United States and its allies have agreed to offer Iran "modest relief" from economic sanctions and access to a portion of the revenue that the country has been denied through these sanctions. No new sanctions will be imposed, Obama said.
All six world powers had sent in their foreign ministers hours before the deal was announced, and several purposely gave the impression it was their participation that was needed to carry the ball across the finish line. Once the ministers arrived, the negotiations set a marathon pace, not ending until about 3 a.m. local time in Geneva (9 p.m. ET).
While the "first step" deal is currently set to last for a period of just six months, it has provided a massive sense of relief on all sides in Geneva as it is expected to make Iran less capable of building a nuclear bomb for the time being, while at the same time easing the financial pain Iran's economy has been enduring under the sanctions.
Perhaps most significantly, it also makes a final comprehensive nuclear agreement between Iran and the world suddenly more possible.
There is little doubt, however, that the sticking points included Iran’s insistence that it has a right to enrich uranium for peaceful purposes, and the tacked-on proposal that Iran stop construction of a heavy water facility in Arak. Iran has said the facility is needed to create medical isotopes for cancer treatments, but it could also make Iran more quickly capable of building a bomb.
How exactly these sticking points were resolved will greatly influence the expected political fallout in the United States and Iran. Some members of Congress are threatening new sanctions in the U.S., and hard-liners in Iran are harshly accusing Rouhani and his Foreign Minister Javad Zarif of giving up too much in the negotiations. Indeed, a sense of national pride appears to drive a rising backlash from even moderates and liberals in Iran.
Adding to the hurdles, the deal is also designed to be not only temporary but reversible depending on whether the promises made by both sides are fully kept. One of the agreements, for example, is that Iran give inspectors broader access to nuclear sites, and allow spontaneous inspections.
Then there is also the matter of Israeli Prime Minister Benjamin Netanyahu's increasingly vociferous objections, and the negative impact the negotiations appear to have had on U.S.-Israeli relations. It will likely also affect U.S. relations with Saudi Arabia, a Sunni nation, which is threatened by signs of improved U.S. relations with Shia Iran.
Any final comprehensive agreement is expected to have vast implications on the political and financial landscape in the Middle East, given Iran's oil resources, and the billions of dollars an end to sanctions could unlock.
Remarkably, the first-step deal announced Sunday, was virtually inconceivable before Rouhani’s dramatic phone conversation with Obama in September.
The speed of the negotiations, which now continue toward a final agreement, are a measure of how much both leaders want to end the nuclear standoff before the window of opportunity closes.
NBC News' Becky Bratu contributed to this report.