It's not just the US, even the Germans have admitted the Iranians have been flouting the agreement since day 1. In any event, the agreement is pointless as the restrictions on Iran's nuclear program are only temporary. Iran is run by regressive fundamentalist zealots - the regime makes Atwood's Handmaids Tale look like a cakewalk. One of the main issues is nuclear proliferation among Arab states if Iran gets a weapon - expect the Saudis and UAE to get weapons in the event Iran builds a nuke. Even Russia and China have reasons to be concerned about an Iranian weapon.