At a moment when American negotiators say they see some signs of movement on the part of Iran toward a broad nuclear deal with the United States, the head of the United Nations nuclear inspection organization declared Friday that Iran had stopped answering the agency’s questions about suspected past efforts to design the components of a bomb. The director general of the International Atomic Energy Agency , Yukiya Amano, said commitments Iran had made to provide more information on what he called “possible military dimensions” had not been carried out. He said that while he had received assurances from Iran’s president, Hassan Rouhani, that he was “willing to clarify the ambiguity” in documents and computer records that appear to show work on a variety of technologies that can be used to detonate a weapon, the cooperation had not been forthcoming. “What is needed now is action,” Mr. […]