Iran: Tangled nuclear dispute with the West

Iran and the United States are scheduled to hold talks on Saturday on Iran's nuclear program, with US President Donald Trump having threatened military action if they cannot agree a deal. Iran's nuclear program has been the subject of a long dispute between it and Western countries that fear it wants to build an atomic bomb, which Tehran denies. Here is a timeline of the dispute:

1957 - Iran and United States signed a nuclear cooperation deal and the United States delivers a research reactor to Iran a decade later.

1970 - Iran ratified the Nuclear Nonproliferation Treaty (NPT), giving it the right to a civilian nuclear program but barring it from seeking an atomic bomb.

1979 - Iran's Islamic revolution upended its ties to major powers, turning former ally the United States into its main foe.

1995 - Russia agreed to finish construction of Iran's planned nuclear power plant at Bushehr, originally started by Germany and shelved after the revolution.

2003 - The UN nuclear watchdog, the International Atomic Energy Agency (IAEA), alleged Iran has not complied with NPT after the revelation it has secretly built a uranium enrichment plant at Natanz and a heavy water plant for plutonium at Arak.

Both can be used to make fuel for nuclear power but they can also be used in atomic warheads.

Iran accepted European proposals for more transparency in its nuclear program including snap IAEA inspections.

2004 - The IAEA said Iran did not provided the transparency it promised. Iran said it would not suspend uranium enrichment activity.

2005 - Russia offered to supply Iran with fuel for Bushehr to stop it developing its own fuel by making enriched uranium or plutonium.

IAEA said Iran was not in compliance with agreements and EU countries halted negotiations.

2006 - Iran resumed work at Natanz, said in April it had enriched uranium for the first time to about 3.5%, far short of the 90% needed for a warhead.

World powers the United States, Russia, China, France, Britain and Germany - later known collectively as the P5+1 offered Iran incentives to halt enrichment.

The United Nations Security Council imposed sanctions on Iran over its enrichment.

2009 - Western countries alleged Iran was building another secret uranium enrichment facility under a mountain at Fordow near Qom.

2010 - Iran started making 20% enriched uranium. The UN Security Council expanded sanctions including an embargo on major weapons systems, as the US and EU tighten their own sanctions.

A computer virus - Stuxnet - deployed aimed at paralyzing the Natanz plant, the start of direct operations against Iranian facilities that Tehran blames on Israel.

2011 - Bushehr nuclear plant started operations. Iran said it was using more advanced centrifuges to expand its 20% enrichment program.

2013 - Former nuclear negotiator Hassan Rouhani was elected Iranian president offering new proposals. He and US President Barack Obama hold a first call between leaders of the countries since 1979.

Iran-P5+1 talks in Geneva resulted in a Joint Plan of Action with steps required by both sides including reducing Iran's enriched uranium stockpile, more IAEA access and some sanctions relief.

2014 - Negotiations on a final deal continued through the year, with Iran halting uranium enrichment to 20% and work at Arak and getting access to oil revenue frozen by sanctions.

US allies in the region, Israel and Saudi Arabia, repeatedly cautioned Washington against a deal, saying Iran could not be trusted and citing its growing sway in the region.

2015 - Iran and the P5+1 agreed the Joint Comprehensive Plan of Action (JCPOA) deal that limits Iran's nuclear work, allowing more inspections and a loosening of sanctions.

2016 - IAEA said Iran had met its commitments under the JCPOA, leading to UN sanctions tied to the nuclear program being lifted.

However, Iran's long-range ballistic missile tests prompt unease despite Tehran saying they could not carry nuclear warheads.

2017 - New US President Donald Trump declared the JCPOA was the "worst deal ever" and unilaterally pulled out. Despite Trump promising a better deal there have been no new talks.

2018 - The US reimposed on Iran.

2019 - With ties between Iran and the West deteriorating, a string of attacks on Gulf oil tankers and other regional energy facilities were blamed by the US on Iran.

2020 - A blast rocks Iran's Natanz plant and a nuclear scientist is assassinated near Tehran with Iran blaming both incidents on Israel.

2021 - With Trump out of the White House, the US and Iran resumed indirect talks but there was little progress.

Iran started enriching uranium to 60% - not too far from 90% needed for a bomb.

There were attacks on Iran's Natanz and a centrifuge factory in Karaj.

2022 - The IAEA accused Iran did not answer questions over uranium traces found at more sites. Iran stopped IAEA inspections and installed more new centrifuges at Natanz.

2025 - Trump returns to the White House and declared Iran must agree to a nuclear deal or there will be bombing.