BERLIN — Iran appears to be complying with a 2015 deal with major powers that was meant to stop it from developing nuclear weapons in exchange for the lifting of economic sanctions, the United Nations nuclear watchdog said Thursday. The United States pulled out of the pact earlier this month, and wants to impose tough sanctions on Iran, while European powers and Tehran say they are committed to keep working together to save the deal. The International Atomic Energy Agency said in Vienna, in its first report since the U.S.