The deal provided Iran sanctions relief for limits on its nuclear program. But now there's new Iranian leadership and more uranium in their stockpile than when Trump abandoned the agreement.

Iran on Sunday described a blackout at its underground Natanz atomic facility an act of "nuclear terrorism," raising regional tensions.

Before the U.S. pulled out, the deal gave Iran money and gave the world assurances that Iran wasn't trying to build nuclear weapons.

Nuclear inspections have been a key part of the Iran nuclear deal. International inspectors stand to permanently lose access to key sites, unless the U.S. and Iran can find a way forward.

Ayatollah Ali Khamenei, Iran's supreme leader, said Sunday that all U.S. sanctions must end before Tehran will return to its commitment under the 2015 nuclear accord.