As the Israeli government and its most ardent backers in the United States continue to ramp up their criticism of the Obama administration’s pursuit of a nuclear deal with Iran, they might do well to heed the lessons from the last time they were involved in arms-length diplomacy with their arch-enemies in Tehran.

Nearly a decade ago, the U.S. Jewish community and the United Nations played a key role in a series of secret negotiations to win the release of thirteen Jews imprisoned in Iran.

Depending on whom you listen to, the process was either proof that negotiations between these archenemies can lead to peace or that an unyielding hard line by the West can force the ayatollahs to capitulate.

In 1999, the story started almost predictably. Security agents arrested thirteen Jewish residents of the southeast Iranian city of Shiraz, including five merchants, a rabbi, two university professors, three teachers in private Hebrew schools, a kosher butcher and a 16-year-old boy, accusing them of spying for Israel. After an elaborate, partially televised show trial, 10 were sentenced to lengthy prison terms, while Israel organized a high-level pressure campaign globally to win their release. The prisoners were gradually freed in small groups, with the news kept under wraps until the barest of details were leaked in March 2003, a month after the last one left Iran for Israel.

But the inside story, never told until now, appears to show that opposite sides can make a deal, no matter how limited the scope. In interviews, the two key players in the negotiations – U.S. Jewish leader Malcolm Hoenlein and Giandomenico Picco, then a UN diplomat – revealed a delicate diplomatic minuet in the shadows that finally coaxed Iran to release the prisoners.

First, however, Israel’s campaign used tried-and-true conventional tactics. Soon after the Shiraz Jews were arrested, U.S. Jewish groups and other Jewish federations worldwide mobilized a pressure campaign against Iran, with demonstrations in front of Iranian embassies worldwide demanding the prisoners’ freedom. “We reached out to governments around the world, religious leaders, civic leaders, human rights organizations, to raise the issue,” said Hoenlein. “The United States had limited leverage with Iran, and certainly Israel didn’t have any leverage there.”

By traditional Western standards, the campaign was a success: it fostered sympathetic media coverage for the cause, and a worldwide chorus of political and diplomatic criticism of Iran. Within Iran, however, the pressure appeared to backfire. Iranian officials dug in their heels, claiming that the campaign by Israel and Jewish groups was yet more proof that the prisoners had been spies. Prosecutors signaled that they would be convicted and possibly sentenced to death.

The possible death sentences were an ominous sign, not just for the prisoners but for Iran’s Jewish community, the largest in the Middle East outside Israel. Despite the years of hardline Islamic theocracy since the 1979 revolution, the ruling ayatollahs had allowed Iran’s estimated 25,000 Jews a discreet amount of breathing space, free to keep Jewish traditions, run synagogues and Jewish schools with support from Jewish groups abroad, and with one guaranteed seat in Parliament. The arrests seemed to portend a broader crackdown.

So what to do? The campaign needed a much less confrontational and more discreet way to reach out to the Iranians. It needed someone with stellar diplomatic skills, someone who was known and trusted in both Washington and Tehran, and who could operate in almost complete secrecy.

Behind the scenes, Hoenlein, the executive vice chairman of the Conference of Presidents of Major American Jewish Organizations, recruited Ted Sorensen, the former adviser, speechwriter, and lawyer for John and Robert Kennedy. Sorensen paid a visit to Picco, then a UN assistant secretary general, and asked for help.

“Ted Sorensen, this famous man of Camelot, came to me and asked me to help,” said Picco. “I couldn’t refuse. I said yes, I would do what I could.”

Picco was known as a rare maverick in the starched world of UN diplomacy. A decade previously, he single-handedly freed 11 Western hostages in Lebanon by repeatedly allowing himself to be snatched off the Beirut streets in the middle of the night by hooded gunmen, shoved into the trunk of a car, and taken to negotiate directly with the captors’ hooded leaders. Picco had excellent contacts in Iran, both from his constant shuttling to Tehran during the hostage negotiations and from his previous role as the chief UN negotiator to end the bloody Iran-Iraq war.

When Sorensen knocked on his door in late 1999, Picco had an apparently obscure job – he had been designated by Secretary-General Kofi Annan to supervise an intellectual gabfest called Dialogue Among Civilizations, which Annan had launched to help Iran’s reformist President Mohammad Khatami bridge his country’s gap with the West.

“Kofi Annan had told me, ‘Look, the Iranians and the Americans know you. Why don’t you take this pompous title, Special Envoy for Dialogue Among Civilizations, get a group of Nobel Prize winners, and why don’t you all write a book about why don’t we love each other,’” Picco recalled wryly. “As part of that process I had to meet many times with Khatami directly, and with other top Iranian leaders. So that was an excellent cover for this operation.”

Picco used a personal touch. “Khatami was a philosopher, a theologian, and he needed to be treated on that level,” Picco said. “He was not a bazaari, a merchant. I had negotiated before with [previous President Hashemi] Rafsanjani, who was totally different. He, Rafsanjani, some could describe as a bazaari negotiator. With Khatami, I insisted that he get nothing in return for releasing the prisoners. If we are civilized, we don’t imprison just for fun. Freeing the prisoners would be a great gesture to the world – the man who launched the Dialogue could also release the white dove.”

But in late June, three days before the verdict was scheduled to be announced, Picco was in his New York office and received an urgent phone call from U.S. Assistant Secretary of State for Near Eastern Affairs Edward Walker. “He told me, ‘Gianni, we have heard from our sources that they are going to get death sentences. They will be executed. You failed.’”

In a panic, Picco phoned his contacts in the Khatami presidency. Cashing in all the diplomatic chits he had gathered with the Iranians over the years, he angrily demanded that no death sentences be handed out. “I used a very banal and risky strategy – I shouted at them, I just shouted. It’s all I could do.”

Days later, the sentences were announced. Three of the thirteen were absolved, and ten were convicted and sentenced to prison terms of four to thirteen years. No death sentences.

Walker did not respond to an interview request for this article.

Jewish groups around the world and human rights organizations condemned the verdict and what they said was the lack of due process throughout the trial. An appeal was mounted, which resulted in the reduction of prison terms from two to nine years.

Behind the scenes, Picco kept negotiating.

Khatami finally agreed to release the Jews – but with two caveats. He asked that Israel end its worldwide pressure campaign. Picco quickly relayed the request to Hoenlein in New York. While Hoenlein now denies that Israel and Jewish groups in the West explicitly agreed to stand down their campaign, he allows that they did effectively just that. “Messages had been communicated about these things,” he said. “There was no deal to that effect. But we felt that once there was an arrangement (to release the prisoners), there was no point in humiliating Iran, to crow about some victory. Our goal was only one thing.”

Khatami also told Picco that he needed to release the prisoners gradually, in small groups, to avoid the appearance of making any concession to Israel or U.S. Jews.

“He told me that he needed ‘decent intervals’ between releases of various batches of prisoners. He was very clear about the ‘decent intervals,’ which he said he knew was a concept coined by Henry Kissinger,” he said, referring to the U.S. request for North Vietnam to allow the Nixon administration a gradual, face-saving exit from the Vietnam War.

The prisoners deal was quietly welcomed by the Clinton administration. In attempt that has been previously reported, Picco worked with Clinton and Khatami aides to try to engineer a meeting between the two leaders during the annual speeches by heads of state at the UN General Assembly in September. The delicate series of protocol steps carried significant risk for both leaders, leaving them open to domestic political backlash if they were seen publicly as deferential to the other.

Both leaders politely sat and listened to each other’s speech – the first time U.S. and Iranian leaders had done so since the 1979 revolution – but a meeting failed to materialize amid the rush of last-minute risk calculations and security logistics.

“This may not seem like much now, just listening to each other’s speeches, but it was a historic gesture,” says Picco. “After two decades of hostility, we had a moment that was right, but we just ran out of time. And then Clinton left office, and the rest is history.”