WASHINGTON — Many paths led to the international agreement to temporarily curb Iran's nuclear program: secret meetings in Oman, formal negotiations in Geneva, and a quiet encounter in New York involving two diplomats and an exquisite silver chalice in the shape of a mythical winged creature.
The latter session led in September to the return of the chalice to Iran, where officials hailed it as a gesture of friendship by the United States. The move was orchestrated by a mid-level diplomat at the U.S. Mission to the United Nations who devised a way to work around a 30-year absence in formal relations.
"I wasn't sure we could pull it off," he said. "They don't talk to us. We don't talk to them."
The diplomat has operated under rules that barred most contact with Iranian officials for his entire career. Even now, because of the sensitivity of relations between the two countries, he was allowed to discuss the exchange only on condition that he and others involved not be identified.
The episode began during the summer, when the Obama administration's Middle East experts met to debate a delicate matter of diplomacy: how to acknowledge the election of Iran's moderate new president, Hassan Rouhani, in a way that might convey goodwill and show respect to the Iranian people.
One expert suggested that President Obama shake Rouhani's hand at the fall summit of the United Nations. Another posed the idea of a video message from Obama to Iranians.
But an Iran specialist came up with another possibility; returning the silver ceremonial chalice. Officials believe it was looted from an Iranian cave and imported illegally. It was seized by U.S. customs in 2003 and stored ever since in a shroud of cotton in a federal warehouse in Queens.
For a decade, Iran had sought return of the chalice, which officials there regarded as part of the country's cultural heritage. Meeting that demand, the Americans thought, could build goodwill for the U.S. and thereby strengthen Rouhani, who had won the presidency in part by promising to improve relations.
Bolstering Rouhani, they thought, would be key to reaching any deal on the nuclear program, which hard-liners in both Iran and the United States were sure to oppose.
"This wouldn't just be a gesture for government officials," said a senior administration official who took part in the meeting. "This would be a gesture with meaning for the people of Iran."
Some experts believe the vessel, known as a rhyton, was crafted in the 7th century BC in what later became the Persian Empire, now Iran. It features three trumpet-shaped cups that sprout from the body of a griffin, a fabled creature that typically has the head and wings of a bird and the body of a lion. On the chalice, the eyes are deep-set and wide open, like those of a bird of prey.
The object was allegedly part of a cache of antiquities found in a cave near the Iraqi border in the 1980s, shortly after Iran's Islamic Revolution.
"These were great treasures from a great civilization," said Fariborz Ghadar, an Iranian scholar who served as a deputy economic minister to Iran's shah. "Their discovery was of great significance to those who consider themselves Persians, who honor that period in history."
In 2003, the chalice surfaced in the hands of a well-known antiquities dealer, Hicham Aboutaam, who ran a firm based in Geneva. As he passed through U.S. customs at Newark International Airport, Aboutaam presented a certificate indicating the vessel was from Syria. He was waved through.
Aboutaam then set out to document the object's value. Three experts he consulted determined it was from Iran; two concluded it was consistent with the antiquities taken from the cave. An art collector was prepared to pay $1 million, but federal investigators caught wind of it. They charged that the object had been taken from Iran illicitly, making its importation to the U.S. illegal. The dealer was prosecuted and paid a $5,000 fine.
The chalice was then placed in a climate-controlled storage unit.
The value of the chalice remains uncertain. Some have maintained that it is not 2,700 years old at all, but a modern fake. But Iranian officials have insisted it is genuine and demanded its return.
In Iran, Ghadar said, seizure of any of the nation's antiquities by the West "was a sign of great disrespect."
When Rouhani announced plans to attend the U.N. General Assembly in New York in September, Obama's advisors decided the moment was right for a gesture.
A day after Obama delivered his annual address to the world body, the American diplomat received an email from Washington, which he read at his desk three blocks from U.N. headquarters. He was instructed to find a way to return the griffin chalice to the Iranians with no fanfare before Rouhani left in two days.