Cutting a nuclear deal with Iranian President Hassan Rouhani and Ayatollah Ali Khamenei would be the easy part for President Obama, who must then persuade both houses of Congress to sign off on the pact. Republicans and many Democrats abhor the idea of lifting sanctions and readmitting oil-rich Iran to the global economy until it disavows all nuclear research and stops meddling through proxies in Iraq, Lebanon, Syria, and Yemen.

Advocating for an Iran truce is a loose coalition of peace groups, think tanks, and former high-ranking U.S. diplomats bound together by millions of dollars given by the Rockefeller family through its $870 million Rockefeller Brothers Fund. The philanthropy, which is run by a board split between family members and outsiders, has spent $4.3 million since 2003 promoting a nuclear pact with Iran, chiefly through the New York-based Iran Project, a nonprofit led by former U.S. diplomats. For more than a decade they’ve conducted a dialogue with well-placed Iranians, including Mohammad Javad Zarif, now Tehran’s chief nuclear negotiator. The Americans routinely briefed officials in the George W. Bush and Obama administrations, including William Burns, Obama’s former deputy secretary of state. Burns hammered out much of an interim nuclear agreement in secret 2013 talks with his Iranian counterparts that paved the way for the current summit in Vienna, where Secretary of State John Kerry leads the U.S. delegation.

The Rockefellers’ Iran foray began in late 2001, after the Sept. 11 attacks. Stephen Heintz, president of the Rockefeller Brothers Fund, convened a board retreat at the Rockefellers’ Pocantico Center in Westchester, just north of New York City, to consider new approaches to the Islamic world at a time when the U.S. was focused on the threat from al-Qaeda. One invited speaker was Seyyed Hossein Nasr, an Iranian-American professor at George Washington University. “He got me thinking more and more about Iran, its geostrategic importance and its relationship to the Sunni world,” says Heintz.

The Rockefeller fund decided to create the Iran Project in cooperation with the United Nations Association of the U.S., a nonprofit that promotes the UN’s work then headed by William Luers, a career diplomat who served as ambassador to Venezuela and Czechoslovakia. Luers made contact with Zarif through Iran’s mission to the UN in New York. He also recruited career diplomats Thomas Pickering, who served as Ronald Reagan’s ambassador to Israel and George H.W. Bush’s ambassador to the UN, and Frank G. Wisner, who served as Reagan’s ambassador to Egypt and whose father was a high-ranking officer in the Office of Strategic Services and then in the CIA. “Each of us came from a special place on the compass,” Wisner says.

With encouragement from the Bush administration, says Heintz, the trio developed a relationship with Zarif, who was stationed in New York representing Iran at the UN. In early 2002, the Iran Project set up a meeting with Iranians affiliated with the Institute for Political and International Studies in Tehran, a think tank with close government ties. It was hosted by the Stockholm International Peace Research Institute at a small hotel outside Stockholm. The Iranians came armed with talking points, Heintz says, and the meetings were stiff and unproductive. The initial goal of developing a road map to restoring relations between Washington and Tehran, along the lines of Nixon’s 1972 Shanghai Communique preceding U.S.-China relations, proved elusive, according to Pickering. After every meeting, Heintz says, Iran Project leaders would brief staffers at the State Department or White House, including Stephen Hadley, Bush’s national security adviser, and Condoleezza Rice, his secretary of state. “As we had no contacts at all with Iran at the time, their insights were very valuable,” says R. Nicholas Burns, who served as under secretary of state for political affairs under Bush.

The secret meetings in European capitals were suspended after Mahmoud Ahmedinejad won Iran’s presidency in 2005. But the group’s relationship with Zarif proved key in helping to jump-start negotiations after he was made foreign minister in 2013 by Rouhani, the newly elected president. A State Department official says the administration welcomes back-channel efforts like the Iran Project’s because “it proves useful both to have knowledgeable former officials and country experts engaging with their counterparts and in reinforcing our own messages when possible.”

The Iran Project kept an eye on public opinion from the start. Among those invited to its events in New York was Robert Silvers, editor of the New York Review of Books, who found them “helpful in framing ideas for a workable nuclear treaty,” he says. The ideas floated at the meetings included letting the Iranians keep a limited capacity for enriching uranium to save face. “But everyone knew that a huge amount depended on how far the Iranians would go.” Silvers published multiple essays detailing the proposals by Pickering and Jessica Mathews, another Iran Project participant who preceded William Burns as president of the Carnegie Endowment for International Peace. The Iran Project’s briefing papers have provided a counterweight to criticism from pro-Israel groups, led by the American Israel Public Affairs Committee, opposed to a deal.

For Wisner, breaking bread with Iranians exorcised a few ghosts. He was on Secretary of State Cyrus Vance’s senior staff during the Iranian revolution and the hostage crisis in 1979 and knew diplomats held at the embassy. “I lived that,” he says. He also remembers listening to his dad planning the military coup that removed Iran’s democratically elected prime minister, Mohammad Mosaddegh, from power in 1953 and replaced him with the U.S.-backed shah, Reza Pahlavi. “They don’t trust us, and we don’t trust them,” says Wisner. He says his father’s role in the Mosaddegh coup didn’t come up in any of the Iran Project meetings. “The Iranians, like us, have made a major political decision to engage,” he says.

The Rockefeller fund has given about $3.3 million to the Ploughshares Fund, a San Francisco-based disarmament group that has spent $4 million since 2010 to promote a deal with Iran and shepherded the peace groups and think tanks it supports to back Obama. “We’re trying to leverage our investments to play on our strengths,” says Joseph Cirincione, its president.

On June 23, when the New York Times ran an op-ed, “The Iran Deal’s Fatal Flaw,” Ploughshares coordinated its grantees’ responses to the claim that the deal would leave Iran capable of producing a nuclear weapon within three months. The Arms Control Association, a nonpartisan group established in 1971, published a rebuttal on its daily blog, which other Ploughshares-affiliated groups sent to their contacts in Congress. “The pro-deal side has done a very good job systematically co-opting what used to be the arms control community and transforming it into an absolutist, antiwar movement,” says Omri Ceren, senior adviser for strategy for the Israel Project, a nonprofit that opposes a deal. “Sometimes, if your goal is stopping the proliferation of weapons of mass destruction, you have to make the hard decision to take military action, or at least signal you’re willing to.” Cirincione says that mistakes the rationale behind the Iran Project. “Iran is the boulder in the road,” he says. “You have to resolve this issue to get to the rest of the nonproliferation agenda. That’s why we’re doing this.”

This story was updated to clarify that allowing Iran to retain uranium enrichment capacity was among ideas proposed by the Iran Project, not one suggested by Robert Silvers.

CORRECTION: The story has been corrected to reflect that Seyyed Hossein Nasr teaches at George Washington University, not Georgetown. 

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