The US unleashed its "toughest ever" sanctions against Iran on Monday. The Trump administration reinstated all sanctions removed under the 2015 nuclear deal, targeting both Iran and states that trade with it. They will hit oil exports, shipping and banks - all core parts of the economy. The sanctions have already sparked mass protests in the oil-rich nation. Thousands of Iranians chanting "Death to America" rallied on Sunday, rejecting calls for talks. Iranian President Hassan Rouhani has vowed to sell his country's oil and break the sanctions.