Iran has committed another breach of its nuclear deal with major powers by enriching uranium with advanced centrifuges, a report by the U.N. nuclear watchdog policing that deal said on Thursday, further fraying the landmark accord. Iran is breaching the restrictions of its deal with major powers step-by-step in response to U.S. sanctions imposed since Washington pulled out of the agreement in May of last year. Washington has repeatedly said it is prepared to hold talks with Iran on a more far-reaching deal, arguing its crippling economic sanctions will force Iran to the negotiating table.