The United States is disappointed with Iran’s failure to engage with a U.N. nuclear agency investigation into suspected atomic bomb research, a U.S. envoy said on Monday. Western officials say Iran must improve cooperation with the long-running International Atomic Energy Agency (IAEA) inquiry as part of a broader diplomatic settlement which Tehran and six world powers aim to reach by a self-imposed Nov. 24 deadline. Negotiators from Iran, the United States, France, China, Russia, Britain, Germany and the European Union meet in Vienna from Tuesday to try to end a long impasse over Tehran’s atomic program that has stoked fears of a new war in the Middle East. Potentially complicating those efforts, an IAEA report on Nov. 7 said Iran was failing to address suspicions it may have worked on designing an atomic bomb. Iran says it has no such aim and that its nuclear program […]