VIENNA -- After 18 days of intense negotiations, the U.S. and five other world powers have reached a deal to freeze Iran's nuclear program for the next decade in exchange for gradual sanctions relief that rolls out as Iran complies with a multi-step process.
The accord will keep Iran from producing enough material for a nuclear weapon for at least 10 years and impose new provisions for inspections of Iranian facilities, including military sites. And it marks a dramatic break from decades of animosity between the United States and Iran, countries that alternatively call each other the "leading state sponsor of terrorism" and the "the Great Satan."
Touting the deal in an early morning news conference from the White House, President Obama said one of the greatest dangers facing the U.S. today was the "risk is that nuclear weapons swill spread to more and more countries, particularly in the Middle East, the most volatile region in our world."
"We have stopped the spread of nuclear weapons in this region," declared Mr. Obama, insisting that, in spite of concerns over Iran's trustworthiness, the "international community will be able to verify that the Islamic Republic of Iran will not be able to develop a nuclear weapon... Every pathway to a nuclear weapon is cut off."
President Obama stressed there would be "very real consequences for a violation" of the agreement by Iran, and warned opponents in the U.S. and Israel that without the agreement there "would be no lasting constraints on Iran's nuclear program."
Iranian Foreign Minister Mohammad Javad Zarif, in an interview with CBS News correspondent Margaret Brennan, said the deal starts to resolve an issue that was responsible for a lot of tension in the Mideast.
"It's a good testimony to the fact that dialogue and engagement and respect work much better than coercion," Zarif said.
The foreign minister decried what he called the "disinformation and misinformation" that has come out against Iran in recent years, especially around their nuclear program, and said this agreement should offer a chance for greater cooperation.
"I believe we had an unnecessary crisis that simply created a smoke screen upon which ISIS could find its foothold in our region and could spread in our region, and now presents us with an existential threat, presents everybody in the region and beyond the region with an existential threat," Zarif said.
U.S. Secretary of State John Kerry said that the U.S. and its partners would have finished the negotiations a long time ago had they been willing to settle for a lesser deal.
In a separate interview with Brennan, Kerry said the deal is designed to be a long-term fix.
"This is a lifetime deal," Kerry said. "It has 10-year components, but then it also has 15-year components."
On crutches and still nursing a broken leg, Kerry also joked that Tuesday was a historic day for him personally because it was the first time in six weeks he had worn a pair of shoes.
The agreement, confirmed in a tweet from European Union foreign policy chief Federica Mogherini which was promptly retweeted Kerry and his Iranian counterpart, will become binding once it is enshrined in an already-written United Nations Security Council resolution.
CBS News foreign affairs analyst Pamela Falk reports diplomats at the Security Council and U.S. administration officials expect a draft Iran resolution to be submitted to the council for discussion and a vote as early as next week.
"Despite all the twists and turns in the talks and a number of extensions, hope and determination enabled us to ovdercome all the difficult moments," said Mogherini, officially announcing the agreement on the Joint Comprehensive Plan of Action.
She said the deal ensured that Iran's nuclear program would "exclusively be peaceful," and that the agreement marked "a shift" in the Iranians' approach to its atomic work.
The economic and financial sanctions -- including a U.S. and European Union oil embargo -- will be lifted as Iran complies with the terms of the deal and as U.N. weapons inspectors verify their compliance.
The essentials of the deal, including the removal of two thirds of Iran's uranium enriching centrifuges -- reducing their number from approximately 19,000 to 6,000 -- the destruction of 98 percent of its stockpile of already-enriched uranium, and other elements, remain the same as what was in the previously-announced framework agreed in Lausanne, Switzerland in April.
In a nod to varying interpretations of that framework by Iran and U.S. officials to their respective constitutencies, Zarif said Tuesday alongside Mogherini, as he prepared to read his statement in Farsi, "don't worry, it's the same."
Iran will remain locked out of the U.S. financial system, and an existing U.S. ban on arms sales will continue. A separate U.N. ban on arms sales will be peeled back over time as Iran verifiably complies with the terms of the agreement.
U.N. Secretary-General Ban Ki-moon said in a statement that he hoped, "and indeed believe - that this agreement will lead to greater mutual understanding and cooperation on the many serious security challenges in the Middle East. As such it could serve as a vital contribution to peace and stability both in the region and beyond."
A senior Iranian official called it an "historic day," and Iranian President Hassan Rouhani took to Twitter to laud the deal as the beginning of a new era "with a focus on shared challenges."
In a separate deal, the head of Iran's atomic program signed an agreement with the International Atomic Energy Agency, the U.N. nuclear watchdog, to take steps to resolve outstanding questions about the country's past research into weapons development and to allow additional inspectors into the country.
IAEA chief Yukiya Amano told reporters the "roadmap" agreed to with the Iranians would "enable the agency, with the cooperation of Iran, to make an assessment of issues relating to possible military dimensions to Iran's nuclear programme by the end of 2015. It sets out a clear sequence of activities over the coming months including a provision by Iran of explanations regarding outstanding issues."
Prior to the announcement, a senior diplomat told the Associated Press that the deal included a compromise between Washington and Tehran that would allow U.N. inspectors to press for visits to Iranian military sites as part of their monitoring duties.
But access at will to any site would not necessarily be granted and even if so, could be delayed, a condition that critics of the deal are sure to seize on as possibly giving Tehran time to cover any sign of non-compliance with its commitments.
The U.S. Congress will have 60 days to review the terms agreed to in Vienna, after which they will vote on the pact. There has been fierce opposition to the deal, even before the details were known, from many Republicans and some Democrats in Washington, and they may try to block implementation of the measures with their votes. Congress does not have the power, however, to completely obstruct the agreement reached by the executive branch with other nations.
Opposition to the deal has also been fierce from Israel, the most entrenched U.S. ally in the Middle East.
Prime Minister Benjamin Netanyahu called the deal a "bad mistake of historic proportions" on Tuesday, adding that it would enable Iran to "continue to pursue its aggression and terror in the region."
In the past, Israel has threatened to carry out a military strike against Iran's nuclear installations. But that option appeared to fade as the U.S.-led group of powers engaged in diplomacy with Iran.
Israel's first course of action looks to be an intense lobbying effort in the U.S. Congress to oppose the deal. Netanyahu spoke against the emerging deal before a joint session of Congress in March. Yet despite strong support among Republicans in Congress, there is little that can be done now.
Under the deal, Tehran would have the right to challenge the U.N request and an arbitration board composed of Iran and the six world powers that negotiated with it would have to decide on the issue.
Still, such an arrangement would be a notable departure from assertions by top Iranian officials that their country would never allow the U.N's International Atomic Energy Agency into such sites. Iran has argued that such visits by the IAEA would be a cover for spying on its military secrets.
The accord will "grant Tehran sanctions relief in exchange for curbs on its nuclear program," the Reuters news agency quotes an Iranian diplomat as saying Tuesday.
"All the hard work has paid off and we sealed a deal. God bless our people," the diplomat told Reuters on condition of anonymity. Another Iranian official confirmed the agreement to Reuters.
The news agency also reports that "Iran has accepted a so-called 'snapback' plan that will restore sanctions in 65 days if it violates" the deal.