It was a promise made during his election campaign.
Donald Trump said the agreement will never bring peace even if Iran complies fully.
He describes it as a disaster and embarrassment for all citizens of the United States.
The agreement was concluded in Vienna on July 14, 2015 after twelve years of crisis and twenty-one months of fierce negotiations between Iran and the five permanent members of the UN Security Council.
It provides for a gradual and conditional lifting of international sanctions imposed on Iran in exchange for the guarantee that Tehran will not acquire nuclear weapons.
Reacting to the US decision, Iranian President Hassan Rouhani accused Donald Trump of “engaging in psychological warfare”.
France, Germany and the United Kingdom who regret the US decision to get out of the Iranian nuclear deal count on working collectively on a broader agreement, Emmanuel Macron says on Twitter just after the announcement of the withdrawal of the United States.