The remarks came one day before a self-imposed deadline for responding to a package of incentives aimed at persuading Iran to voluntarily stop enriching uranium.

In a speech to a group described by Iranian television news as 'Islamic intellectuals', Ayatollah Khamenei stayed consistent with Iran's confrontational, no-backing-down tone, while at the same time remaining vague in terms of substance. He gave no indication of what 'forceful' meant, though over the past week, and again today, officials said Iran would refuse to give up enrichment.

"The Islamic Republic of Iran has made up its mind based on the experience of the past 27 years to forcefully pursue its nuclear program and other issues it is faced with and will rely on God," he said in remarks reported on the Iranian state news agency. "Be patient and hopefully we will taste a sweet outcome."

Iran's defiance was offered up on several fronts today, even as Iranian officials said that within 24 hours the leadership would give a formal response to the incentive proposal offered by the United States, Russia, China, Britain, France and Germany. One official, in an interview with the Iranian Fars News Agency, said Tehran was moving ahead with plans to start up a 'heavy water' plant that would feed a nuclear reactor. The Associated Press reported that Iran turned inspectors away from a nuclear facility in Natanz, which would be a violation of the Nuclear Nonproliferation Treaty.

One day earlier, Iran held military exercises in which it test fired surface-to-surface missiles during the second day of war games.

But amid the tough-talk and missile firing, Tehran did not offer up any details of how it would respond to the incentive package. The United States and Europe have accused Iran of wanting to develop weapons, while Iran has insisted it is pursuing civilian peaceful nuclear energy. Though Iran had initially spoken favorably about the incentive package, its tone changed last month when the United Nations Security Council ordered Iran to halt enrichment by Aug. 31 or face political and economic sanctions.

"Arrogant powers and the U.S. are putting their utmost pressure on Iran while knowing Iran is not pursuing nuclear weapons," Ayatollah Khamenei said.

Iranian officials have also threatened to keep their nuclear work hidden from all public view if the Security Council tries to force it to stop. Iran's chief national security official and lead nuclear negotiator, Ali Larijani, was quoted by the Iranian television news earlier this month as saying that under the Nuclear Nonproliferation Treaty, "if we are threatened we can act in secret."

He went on to say Iran would interpret sanctions as just such a threat.

Political analysts in Tehran with personal relationships with people in the government and security agencies said they were expecting Iran to offer a response that amounted to conditional approval of the incentive package - accepting some elements in whole, calling for negotiating over other elements, while rejecting the demand that it completely stop uranium enrichment.

At the same time, they said, the Iranian leadership was already preparing for sanctions, but these leaders were also hoping that by leaving room for additional negotiations, China and Russia would help Iran buy some more time without sanctions.

"As usual, nobody really expects Iran to give a definitive answer to the package," said Mohammad Hossein Hafezian, a senior researcher at the Center for Scientific Research and Middle East Strategic Studies in Tehran. "It is very difficult for this system to make compromise - to reverse or retreat."

For Iran's leadership, negotiations over the nuclear program are a flashpoint in an internal debate over how far to integrate Iran into the international community in political, diplomatic and economic terms, political analysts and diplomats here said. Reaching an agreement with Europe and the United States on the nuclear program could open a door that the clerical leadership here is not prepared to open, fearful that foreign investment and renewed diplomatic relations with the West would undermine their strict authority and their ideological grip on power.

"The purity of their system would be broken, lost," Dr. Hafezian said. "They don't want any kind of power sharing. They want to maintain final say in anything they do."

In addition to responding to the incentive offer, officials said today that President Mahmoud Ahmadinejad would formally announce next week Iran's decision regarding the demand that it stop uranium enrichment by the end of the month. That announcement, however, is expected to be substantively redundant, at least in the short term.

It was unclear how Iran would ultimately respond if it were saddled with biting sanctions. Dr. Hafezian said that there was speculation that if Tehran found itself under too much international pressure, it might ultimately accept a Russian proposal to conduct enrichment in Russia, and not in Iran. But for the time being, the slogans coming from officials here pointed in only one direction - a refusal to suspend its nuclear program.

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