The Iran Nuclear Talks Explained Talks in Vienna starting Tuesday will try to bring both the United States and Iran back into compliance with the 2015 nuclear deal. It won’t be easy. Women walking past a mural in Tehran in May 2019, a year after President Donald J. Trump withdrew the United States from the deal limiting Iran’s nuclear activities.Credit...Abedin Taherkenareh/EPA, via Shutterstock April 5, 2021, 2:40 p.m. ET BRUSSELS — In Vienna on Tuesday, the signers of the 2015 Iran nuclear deal will come together with what would appear to be a simple task. They want to restore compliance with an agreement that put strict controls on Iran’s nuclear enrichment, to ensure that it cannot build a nuclear weapon, in return for the lifting of punishing economic sanctions.