By Dave Clark
The United States and Europe have begun preparing to lift the trade sanctions that have hobbled the Iranian economy as a historic nuclear deal came into effect.
The procedure to lift the embargo began on Sunday, 90 days after the UN Security Council endorsed the accord signed in Vienna in July, a milestone referred to as "Adoption Day."
But foreign firms will not be able to resume ties with Iran's oil industry and banks right away - sanctions will remain in place until Iran fulfils its end of the bargain.
The next stage in the process - "implementation day" - will only come when UN nuclear watchdog the IAEA confirms Iran has dramatically scaled back its nuclear program.
Tehran will have to surrender or dilute the bulk of its enriched nuclear fuel stocks, dismantle most of its centrifuges and halt a reactor capable of making plutonium.
Only then will the sanctions "waivers" that US President Barack Obama ordered his administration to issue on Sunday come into effect and trade can begin to resume.
"If fully implemented, it will bring unprecedented insight and accountability to Iran's nuclear program forever," US Secretary of State John Kerry promised.
"This is an important day for all of us and a critical first step in the process of ensuring that Iran's nuclear program will be exclusively for peaceful purposes."
Ali Akbar Salehi, the head of Iran's nuclear agency, was awaiting President Hassan Rouhani's order to remove thousands of centrifuges from sites at Natanz and Fordo.
"What we need to accomplish is a huge task. We hope to start this week or next week," he told state television.
Dismantling the centrifuges, which enrich uranium, was part of a July 14 deal, known as the Joint Comprehensive Plan of Action, between Iran and six world powers.
As well as slashing the number of centrifuges at Natanz and Fordo to around 6,000, Iran will have to satisfy the IAEA that its Arak reactor cannot be used for military purposes.