VIENNA — Iran has defied international demands to rein in its nuclear program and has increased its stockpile of uranium enriched to near weapons-grade levels, according to a confidential report by the United Nations’ nuclear watchdog seen Tuesday by The Associated Press. The report by the International Atomic Energy Agency said that as of Oct. 26, Iran has 182.3 kilograms (401.9 pounds) of uranium enriched up to 60%, an increase of 17.6 kilograms (38.8 pounds) since the last report in August .