VIENNA - The United States is disappointed with Iran's failure to engage with a UN nuclear agency investigation into suspected atomic bomb research, a US 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 November 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.
