Senior U.S. official : The United States is not going to allow North Korea to threaten the world with nuclear weapons. Iran admits to existence of second uranium enrichment plant , U.N. agency says . President Obama speaks with Chinese President Hu Jintao , left , at the Group of 20 plenary session Friday . Officials : President Obama recently shared sensitive intelligence with Russia , China . Administration 's goal is to impose new sanctions on Iran , officials say .
Senior U.S. official : The United States is not going to allow North Korea to threaten the world with nuclear weapons. Iran admits to existence of second uranium enrichment plant , U.N. agency says . Officials : President Obama recently shared sensitive intelligence with Russia , China . Administration 's goal is to impose new sanctions on Iran , officials say .