New U.S. sanctions are sending an economic shock through Iran even before they take effect.
Since President Donald Trump withdrew the U.S. from the nuclear deal in May, Iran’s manufacturers, Persian-rug exporters and shopkeepers have increasingly struggled to make transactions in dollars for imports of needed supplies. Foreign companies are winding down contracts and the threat of sanctions has scared away big foreign banks, many of which paid billions of dollars in fines to U.S. regulators for sanctions violations in the...