The Treasury Department has imposed sanctions on Iranian Foreign Minister Mohammad Javad Zarif, in the latest move by the U.S. to ratchet up tensions after the Trump administration backed out of the 2015 Iran nuclear deal. The highly unusual move to sanction another nation’s top diplomat comes ahead of the annual U.N. General Assembly in New York City in September. The State Department said it would decide whether to grant Zarif a travel visa on a “case by case basis.”