Just after the lightning takeover of Baghdad by U.S. forces three years ago, an unusual two-page document spewed out of a fax machine at the Near East bureau of the State Department. It was a proposal from Iran for a broad dialogue with the United States, and the fax suggested everything was on the table -- including full cooperation on nuclear programs, acceptance of Israel and the termination of Iranian support for Palestinian militant groups.

But top Bush administration officials, convinced the Iranian government was on the verge of collapse, belittled the initiative. Instead, they formally complained to the Swiss ambassador who had sent the fax with a cover letter certifying it as a genuine proposal supported by key power centers in Iran, former administration officials said.

Last month, the Bush administration abruptly shifted policy and agreed to join talks previously led by European countries over Iran's nuclear program. But several former administration officials say the United States missed an opportunity in 2003 at a time when American strength seemed at its height -- and Iran did not have a functioning nuclear program or a gusher of oil revenue from soaring energy demand.

"At the time, the Iranians were not spinning centrifuges, they were not enriching uranium," said Flynt Leverett, who was a senior director on the National Security Council staff then and saw the Iranian proposal. He described it as "a serious effort, a respectable effort to lay out a comprehensive agenda for U.S.-Iranian rapprochement."

While the Iranian approach has been previously reported, the actual document making the offer has surfaced only in recent weeks. Trita Parsi, a Middle East expert at the Carnegie Endowment for International Peace, said he obtained it from Iranian sources. The Washington Post confirmed its authenticity with Iranian and former U.S. officials.

Parsi said the U.S. victory in Iraq frightened the Iranians because U.S. forces had routed in three weeks an army that Iran had failed to defeat during a bloody eight-year war.

The document lists a series of Iranian aims for the talks, such as ending sanctions, full access to peaceful nuclear technology and a recognition of its "legitimate security interests." Iran agreed to put a series of U.S. aims on the agenda, including full cooperation on nuclear safeguards, "decisive action" against terrorists, coordination in Iraq, ending "material support" for Palestinian militias and accepting the Saudi initiative for a two-state solution in the Israeli-Palestinian conflict. The document also laid out an agenda for negotiations, with possible steps to be achieved at a first meeting and the development of negotiating road maps on disarmament, terrorism and economic cooperation.

Newsday has previously reported that the document was primarily the work of Sadegh Kharazi, Iran's ambassador to France and nephew of Iranian Foreign Minister Kamal Kharazi and passed on by the Swiss ambassador to Tehran, Tim Guldimann. The Swiss government is a diplomatic channel for communications between Tehran and Washington because the two countries broke off relations after the 1979 seizure of U.S. embassy personnel.

Leverett said Guldimann included a cover letter that it was an authoritative initiative that had the support of then-President Mohammad Khatami and supreme religious leader Ali Khamenei.

Secretary of State Condoleezza Rice has stressed that the U.S. decision to join the nuclear talks was not an effort to strike a "grand bargain" with Iran. Earlier this month, she made the first official confirmation of the Iranian proposal in an interview with National Public Radio.

"What the Iranians wanted earlier was to be one-on-one with the United States so that this could be about the United States and Iran," said Rice, who was Bush's national security adviser when the fax was received. "Now it is Iran and the international community, and Iran has to answer to the international community. I think that's the strongest possible position to be in."

Current White House and State Department officials declined to comment further on the Iranian offer.

Paul R. Pillar, former national intelligence officer for the Near East and South Asia, said that it is true "there is less daylight between the United States and Europe, thanks in part to Rice's energetic diplomacy." But he said that only partially offsets the fact that the U.S. position is "inherently weaker now" because of Iraq. He described the Iranian approach as part of a series of efforts by Iran to engage with the Bush administration. "I think there have been a lot of lost opportunities," he said, citing as one example a failure to build on the useful cooperation Iran provided in Afghanistan.

Richard N. Haass, head of policy planning at the State Department at the time and now president of the Council on Foreign Relations, said the Iranian approach was swiftly rejected because in the administration "the bias was toward a policy of regime change." He said it is difficult to know whether the proposal was fully supported by the "multiple governments" that run Iran, but he felt it was worth exploring.

"To use an oil analogy, we could have drilled a dry hole," he said. "But I didn't see what we had to lose. I did not share the assessment of many in the administration that the Iranian regime was on the brink."

Parsi said that based on his conversations with the Iranian officials, he believes the failure of the United States to even respond to the offer had an impact on the government. Parsi, who is writing a book on Iran-Israeli relations, said he believes the Iranians were ready to dramatically soften their stance on Israel, essentially taking the position of other Islamic countries such as Malaysia. Instead, Iranian officials decided that the United States cared not about Iranian policies but about Iranian power.

The incident "strengthened the hands of those in Iran who believe the only way to compel the United States to talk or deal with Iran is not by sending peace offers but by being a nuisance," Parsi said.