VIENNA — Iran and six major world powers reached a nuclear deal on Tuesday, capping more than a decade of negotiations with an agreement that could transform the Middle East.

President Obama hailed a step toward a “more hopeful world” and Iran’s President Hassan Rouhani said it proved that “constructive engagement works.” 

But Israel pledged to do what it could to halt what it called an “historic surrender.”

The agreement will now be debated in the U.S. Congress, but Obama said he would veto any measure to block it.

Under the deal, sanctions imposed by the United States, European Union and United Nations will be lifted in return for Iran agreeing long-term curbs on a nuclear program that the West has suspected was aimed at creating a nuclear bomb.

The agreement is a political triumph for both Obama, who has long promised to reach out to historic enemies, and Rouhani, a pragmatist elected two years ago on a vow to reduce the isolation of his nation of almost 80 million people.

Both face skepticism from powerful hardliners at home in nations that referred to each other as “the Great Satan” and a member of the “Axis of Evil”.

“Today is the end to acts of tyranny against our nation and the start of cooperation with the world,” Rouhani said in a televised address. “This is a reciprocal deal. If they stick to it, we will. The Iranian nation has always observed its promises and treaties.”

For Obama, the diplomacy with Iran, begun in secret more than two years ago, ranks alongside his normalization of ties with Cuba as landmarks in a legacy of reconciliation with foes that tormented his predecessors for decades.

“History shows that America must lead not just with our might but with our principles,” he said in a televised address. “Today’s announcement marks one more chapter in our pursuit of a safer, more helpful and more hopeful world.”

Republican opposition

Republicans lined up to denounce the deal. Presidential candidate Lindsey Graham, a senator from South Carolina, called it a terrible deal that would make matters worse. Former senator Rick Santorum, another candidate, said the administration had capitulated to Iran.

The Republican-controlled Congress has 60 days to review the accord, but if it votes to reject it Obama can use his veto, which can be overridden only by two-thirds of lawmakers in both houses. That means dozens of Obama’s fellow Democrats would have to rebel against one of their president’s signature achievements to kill it, an unlikely prospect.

While the main negotiations were between the United States and Iran, the four other U.N. Security Council permanent members, Britain, China, France and Russia, are also parties to the deal, as is Germany.

Enmity between Iran and the United States has loomed over the Middle East for decades.

Iran is the predominant Shi’a Muslim power, hostile both to Israel and to Washington’s Sunni Muslim-ruled Arab friends, particularly Saudi Arabia. Allies of Riyadh and Tehran have fought decades of sectarian proxy wars in Syria, Lebanon, Iraq and Yemen.

But there are also strong reasons for Washington and Tehran to cooperate against common foes, above all “Islamic State”.

British Foreign Secretary Philip Hammond told reporters that the deal was about more than just the nuclear issue:

“The big prize here is that, as Iran comes out of the isolation of the last decades and is much more engaged with Western countries, Iranians hopefully begin to travel in larger numbers again, Western companies are able to invest and trade with Iran, there is an opportunity for an opening now.”

“Historic mistake”

Still, Washington’s friends in the region were furious, especially Israel, whose prime minister, Benjamin Netanyahu, has cultivated a close relationship with Obama’s Republican opponents in Congress.

“Iran will get a jackpot, a cash bonanza of hundreds of billions of dollars, which will enable it to continue to pursue its aggression and terror in the region and in the world,” he said. “Iran is going to receive a sure path to nuclear weapons.”

His deputy foreign minister, Tzipi Hotovely, denounced an “historic surrender” and said Israel would “act with all means to try and stop the agreement being ratified”, a clear threat to use its influence to try and block it in Congress.

Saudi Arabia’s foreign minister said Iran should use a nuclear deal to improve its economy, and not to pursue “adventures” in the Middle East.

“We hope that … if the deal is implemented that the Iranians will use this deal in order to improve the economic situation in Iran and to improve the lot of its people … and not use it for adventures in the region,” Foreign Minister Adel al-Jubeir said during a photo opportunity with Kerry.

“If Iran should try to cause mischief in the region, we’re committed to confront it resolutely.”

Jubeir’s remarks were the first public comments on the nuclear agreement by a senior Saudi official.

“We have learned as Iran’s neighbors in the last 40 years that goodwill only led us to harvest sour grapes,” a Saudi official who asked to remain anonymous told Reuters.

Global implications

The deal opens the door for global corporations to invest in the Iranian economy, which has massive potential. Iran is a country of 77 million people, with the fourth largest oil reserves and second largest natural gas in the world. Iranian oil and gas will flow legally in the world’s market again.

Putting some of the complicated details of the deal might prove problematic, but the trust established during the 18-month negotiations has passed more serious obstacles in the lead to the announcement of the agreement. 

With the exception of Israel, Saudi Arabia, Congressional Republicans and some Iranian hardliners, there seem to be a global consensus about endorsing the agreement. 

Carl Bildt, Sweden’s former prime minister, said the agreement should earn the negotiators a Nobel Peace Prize. 

“I think the work of the Nobel Committee of the Norwegian Parliament this year just got much easier,” he tweeted Tuesday. 

Russian President Vladimir Putin phoned Obama congratulating him on the agreement. French President Francois Hollande has called on Iran for help in the Syrian conflict during a Bastille Day speech in which he praised a landmark Iranian nuclear agreement.

Hollande’s statement reflects a willingness from the international community to work with Iran on regional issues, where the Islamic Republic can have a positive role.

For decades, Iran has been accused of supporting terrorism and sponsoring instability in the region.

While Western powers, led by the United States, have put their differences aside to support the Iraqi government against ISIS, U.S. Iranian policies, clash in Syria, where the disagreements are much deeper.

Iran has been an ally of Syrian President Bashar Assad, supporting him with money, men and weapons. However, the United States insists that Assad must go in order to end the war. 

The Syrian crisis will be a telling challenge for the deal, which will test its political implications beyond the deal. 

Who is Zarif

Leading the Iranian negotiators in Vienna and other European cities was Javad Zarif. 

The Iranian foreign minister, whose first tweet proclaimed his wish to interact and stay in touch with the world, is now the broker between his volatile government and the world’s six mightiest powers.

Zarif and Kerry now call each other by their first name. 

“That’s one of the first things you Americans do,” Zarif told the New Yorker. “Had I not been in the U.S. for such a long time, I would have been astonished for the Secretary of State of the adversary to start calling me by my first name.”

The magazine described the foreign minister as “affable man, with a disarmingly unrevolutionary grin, a quick wit, and the steely tenacity of a debater.”

Pressure from hardliners has led him to change his gotee into a conservative short beard after taking office in 2013.

Born in Tehran in 1960, he is Iran’s former ambassador to the United Nations. 

“In order to practice dialogue, you need to be able to set aside your assumptions and try to listen more than you want to talk,” the New Yorker quoted him as saying. “It’s not always politically correct to be able to do that, but it can give you a better sense of the reality. I have benefitted from the knowledge and the information that all these people have been able to provide to me. I have disagreements with some and more agreements with others. But that doesn’t mean I cannot listen to those I disagree with.”