President Bush has warned that Iran must stop what he said is a secret nuclear weapons program. "It is very important for the world to come together to make it very clear to Iran that there will be universal condemnation, if they continue with a nuclear weapons program," he said.

The warnings come after U.N. inspectors this year found traces of weapons-grade enriched uranium at power plants in Iran.

Iran insists its nuclear program is peaceful.

Iranian Foreign Minister Kamal Kharrazi told the United National General Assembly his country is complying with all treaties dealing with non-proliferation of weapons of mass destruction. He spoke through a translator, saying "The political pressure against the Islamic Republic of Iran to set aside its inalienable rights to develop peaceful nuclear technology is, unfortunately, mounting in circumstances where some nuclear weapons states are testing advanced tactical weapons programs."

Mr. Kharrazi indicated his country would not meet the IAEA's October 31 deadline to provide proof that its nuclear program is purely for peaceful purposes.

But Iran political expert Farideh Farhi of the University of Hawaii said Iran's final response depends on the power struggles between hard-liners and reformists in Tehran. "The seeming united stance taken by Europe and the United States has surprised many in Europe, and has opened the floodgate for domestic discussions about what to do and why Iran finds itself in the current situation," she said.

Ms. Farhi said pundits and politicians have viewed Iran's pursuit of a nuclear program as either a legitimate means of deterrence, or a bargaining chip in its foreign policy, much like North Korea.

"In this way, nuclear weapons are seen as an asset when dealing with Washington - the only way of forcing the United States to adopt a more cautious approach accompanied with respect," she said.

Ms. Farhi said the hard-liners also are shifting the debate from nuclear strategy to sovereignty. "This is something, given the international double standards on the issue, (which) resonates with the population. Iran sits, after all, right in the middle of a region with neighbors that have declared or undeclared nuclear weapons programs."

Still, some experts like Magnus Ranstorp say Iranian fears of direct U.S. action will affect how the government responds to U.N. demands to clarify its nuclear capabilities. Mr. Ranstorp is director of the Center for Terrorism and the Study of Violence at Saint Andrews University in Scotland.

"I wouldn't say that the U.S. would precipitate taking any military action, but certainly, I think, the Iranians are quite nervous right now [about] what are the U.S. intentions," he said.