Who agreed to this?
Iran and six powers including, the U.S. Russia, China, Britain, France and Germany, agreed to the terms July 14. However, it was not until Saturday that there was proof that it had been implemented.
What does lifting economic sanctions mean for Iran?
The deal unlocks some $100 billion in frozen assets. It also opens the path to new oil, trade and business opportunities for the country's struggling economy.
Abbas Akhondi, the Iranian transport minister, said his country had reached a deal with the European consortium Airbus to buy 114 passenger planes once the sanctions are lifted.
The U.N. Security Council also lifted sanctions against Bank Sepah and Bank Sepah International Sunday. The bank's assets were frozen in 2007 because of its reported involvement with Iran's nuclear program.
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Who are the Americans released?
Three Americans have been released under the negotiated prisoner exchange with Iran.
Washington Post reporter Jason Rezaian, former U.S. Marine Amir Hekmati and pastor Saeed Abedini were flown from Iran to Switzerland then brought to a U.S. military hospital in Germany, for medical treatment. It took longer than expected for their travel after their plane had not taken off for unexplained reasons Saturday, according to The Washington Post.
A fourth prisoner, Nosratollah Khosravi-Roodsari, decided not to leave Iran, according to CNN.
The editor of The Washington Post said Rezaian is in "good spirits" following his release. Post editors hope to meet with Rezaian Monday.
Rezaian is a dual Iran-U.S. citizen convicted of espionage by Iran in a closed-door trial in 2015. The Post and the U.S. government have denied the accusations, as has Rezaian. He had been held more than 544 days.
A fifth American was released separately. The student, identified as Matthew Trevithick, was detained 40 days after traveling to Iran in September as part of a four-month language program.
Will the U.S. also release Iranians in custody?
In exchange for the release of the Americans, the U.S. will either pardon or drop charges against seven Iranians — six of them dual citizens — accused or convicted of violating U.S. sanctions. The U.S. will also drop Interpol "red notices" — essentially arrest warrants — on about 14 Iranians outside the U.S, according to The Washington Post.
What does the deal mean for Iran's nuclear program?
All nuclear programs, from uranium mining to research facilities, will be monitored and inspected under the deal. The IAEA inspections could last up to 15 years, with an option to re-impose sanctions if parts of it are broken.
The restrictions aim to increase the time Iran would need to make enough fissile material for a nuclear weapon from several months to a year. This is done through caps on Tehran's ability to enrich uranium. Under the deal, Iran committed to reduce its operating centrifuges enriching uranium by two-thirds.