"Some of the deal’s opponents faulted these so-called sunset provisions, saying they would only delay Iran building a bomb while sanctions relief would allow it to underwrite terrorism in the region," the organization said. ????? ???????  

Many of the restrictions on Iran’s nuclear program "have expiration dates," according to the Council on Foreign Relations, noting for example that centrifuge restrictions would be lifted after 10 years and limits on how much low-enriched uranium Iran can possess after 15 years. ????????????  

If all parties adhered to the deal, experts held that it likely would have prevented Iran from obtaining a nuclear weapon for more than a decade, according to the Council on Foreign Relations. Should Iran try to build a nuclear weapon, sanctions would go back into effect. ?????  

The deal went into effect on Jan. 16, 2016, after the IAEA verified that Iran had completed steps, including shipping 25,000 pounds of enriched uranium out of the country, dismantling and removing two-thirds of its centrifuges and allowing for more extensive international inspections of its nuclear facilities. ????? ???????  

"In exchange, Iran received economic sanctions relief from nuclear-related sanctions" only after the International Atomic Energy Agency verified Tehran had completed certain requirements under the deal. ????????????