Iran said Wednesday it would stop complying with some of its commitments under the 2015 nuclear deal, escalating tensions with the U.S. and moving closer to a breakdown of the landmark accord. President Hassan Rouhani said Wednesday’s move didn’t mean Iran was withdrawing from the nuclear deal, and the steps don’t immediately breach the agreement. But Mr. Rouhani warned of a step-by-step withdrawal from further commitments if European countries didn’t live up to their obligations. …