Defending his efforts to halt the Iranian nuclear threat, U.S. President Barack Obama said Sunday, November 13, that the economic sanctions against the country have had "enormous bite," and that he is united with Russian and Chinese leaders in ensuring Iran does not develop an atomic weapon and unleash an arms race across the Middle East, AP reported.

Obama, at a news conference that closed an Asia-Pacific economic summit, did not specifically say he would consider military action if Tehran were to persist in arming itself with a nuclear weapon. But he added: "We are not taking any options off the table. Iran with nuclear weapons would pose a threat not only to the region but also to the United States."

For the U.S. President, the news conference was his first opportunity to address a report Friday from the International Atomic Energy Agency that provided new evidence that Iran's nuclear program includes clandestine efforts to build a bomb.

The report alleges Iran has been working to acquire equipment and weapons design information, testing high explosives and detonators and developing compute models of a warhead's core. It is the most unequivocal evidence yet that the Iranian program ranges far beyond enriching uranium for use in energy and medical research, as Iran insists.

In meetings Saturday with Russian President Dmitry Medvedev and Chinese President Hu Jintao, Obama sought to rally support for putting new pressure on Iran's regime. But there was little public sign either country was ready to drop its opposition to additional sanctions through the United Nations.

Obama insisted the countries are working on the next steps.