Vienna, July 14

After 18 days of intense and often fractious negotiation, world powers and Iran struck a landmark deal today to curb Iran’s nuclear programme in exchange for billions of dollars in relief from international sanctions — an agreement designed to avert the threat of a nuclear-armed Iran and another US military intervention in the Muslim world.

The accord will keep Iran from producing enough material for an atomic weapon for at least 10 years and impose new provisions for inspections of Iranian facilities, including military sites.

The deal “is not built on trust, it is built on verification,” President Barack Obama declared from the White House, in a statement carried live on Iranian state TV. He said all potential pathways to an Iranian nuclear weapon have been cut off.

In Tehran, Iranian President Hassan Rouhani said “a new chapter” has begun in his nation’s relations with the world.

The two leaders spoke moments after the formal announcement of the so-called Joint Comprehensive Plan of Action, whose completion comes after more than two weeks of furious diplomacy during which negotiators blew through three self-imposed deadlines.

Secretary of State John Kerry, who did most of the bargaining with Iranian Foreign Minister Mohammad Javad Zarif, said persistence paid off. “Believe me, had we been willing to settle for a lesser deal we would have finished this negation a long time ago,” he told reporters.

The breakthrough came after several key compromises. Iran agreed to the continuation of a UN arms embargo on the country for up to five more years, though it could end earlier if the International Atomic Energy Agency definitively clears Iran of any current work on nuclear weapons. A similar condition was put on UN restrictions on the transfer of ballistic missile technology to Tehran, which could last for up to eight more years, according to diplomats.

Washington had sought to maintain the ban on Iran importing and exporting weapons, concerned that an Islamic Republic flush with cash from the nuclear deal would expand its military assistance for Syrian President Bashar Assad’s government, Yemen’s Houthi rebels, the Lebanese militant group Hezbollah and other forces opposing America’s Mideast allies such as Saudi Arabia and Israel.

Iranian leaders insisted the embargo had to end as their forces combat regional scourges such as the Islamic State. And they got some support from China and particularly Russia, which wants to expand military cooperation and arms sales to Tehran, including the long-delayed transfer of S-300 advanced air defence systems — a move long opposed by the United States.

Another significant agreement will allow UN inspectors to press for visits to Iranian military sites as part of their monitoring duties, something the country’s supreme leader, Ayatollah Ali Khamenei, had long vowed to oppose. However, access isn’t guaranteed and could be delayed, a condition that critics of the deal are sure to seize on as possibly giving Tehran time to cover up any illicit activity.

Under the accord, which runs almost 100 pages, Tehran would have the right to challenge the U.N request and an arbitration board composed of Iran and the six world powers would then decide on the issue. The IAEA also wants the access to complete its long-stymied investigation of past weapons work by Iran, and the US says Iranian cooperation is needed for all economic sanctions to be lifted.

The economic benefits for Iran are potentially massive. It stands to receive more than $100 billion in assets frozen overseas, and an end to a European oil embargo and various financial restrictions on Iranian banks.

Joint Comprehensive Plan of Action

•    The accord will keep Iran from producing enough material for an atomic weapon for at least 10 years

•    Iran agreed to the continuation of a UN arms embargo on the country for up to five more years

•    Agreement will allow UN inspectors to press for visits to Iranian military sites as part of their monitoring duties

•    Iran stands to receive more than $100 billion in assets frozen overseas, and an end to a European oil embargo