[Answer] In what year did Iran and several other countries, led by the U.S., reach a controversial nuclear agreement that the U.S. fully exited this week by reinstating sanctions on Iran?

Step 1 : Introduction to the question "In what year did Iran and several other countries, led by the U.S., reach a controversial nuclear agreement that the U.S. fully exited this week by reinstating sanctions on Iran?"

...The Joint Comprehensive Plan of Action, known commonly as the Iran nuclear deal or Iran deal, is an agreement on the nuclear program of Iran reached in Vienna on 14 July 2015 between Iran, the P5+1, and the European Union.