The payoff to Iran is an injection of billions of dollars into its crippled economy over the next six months from the suspension of some sanctions though other sanctions remain in place.
In part a reflection of a thaw between Washington and Tehran, the moves coincidentally occurred on the 33rd anniversary of the end of the Iran hostage crisis. The holding of 52 Americans for 444 days by radical Iranian students that ended Jan. 20, 1981 was followed by more than three decades of U.S.-Iranian enmity, which only began to ease last year with signs that Iran was ready to meet U.S. demands and scale back its nuclear activities.
The Europeans are aiming to start negotiations on a final deal in February, though no date or venue has been agreed on yet. Iranian Foreign Minister Mohammad Javad Zarif said Saturday that Tehran is ready to enter talks as soon as the interim deal goes into force.
In the first step of the interim accord, Iranian state TV said authorities disconnected cascades of centrifuges producing 20 percent enriched uranium at the Natanz facility in central Iran. The broadcast said international inspectors were on hand to witness the stoppage before leaving to monitor suspension of enrichment at Fordo, another site also in central Iran.
Iran also started Monday to convert part of its stockpile of 20-percent enriched uranium to oxide, which can be used to produce nuclear fuel but is difficult to reconvert for weapons use, the official IRNA news agency said.
After receiving independent confirmation of the steps from the United Nations watchdog, the International Atomic Energy Agency, E.U. foreign ministers in Brussels approved the partial sanctions suspension.
The White House also announced the suspension of some U.S. sanctions on Iran.
"These actions represent the first time in nearly a decade that Iran has verifiably enacted measures to halt progress on its nuclear program," White House press secretary Jay Carney said in a statement. He said Iran is also providing U.N. inspectors with increased transparency, including more frequent and intrusive inspections.
Under the deal reached in November in Geneva, Iran agreed to halt its 20 percent enrichment program but continue enrichment up to 5 percent.