The end of Iran's Islamic Revolution
Of course, one explanation for the prolonged bilateral freeze is the warped discourse of what George W. Bush foolishly called the "global war on terror", in which Iran, along with Iraq and North Korea, was cast as part of an international "axis of evil". As a result, US officials viewed any move towards diplomatic normalisation as unacceptable "appeasement".
But the Bush administration's moralistic foreign policy merely reinforced America's stance since Iran's 1979 Islamic Revolution. And it is in the history and course of that revolution that a fuller and more compelling explanation of recent events is to be found.
Forget the French Revolution as a model: the so-called Thermidorian Reaction, when moderates ended Robespierre's Reign of Terror, was an exception to the pattern of modern revolutions. The typical pattern during our living memory is that the hardliners come after the moderates. In the Soviet Union, for example, it was hardliners after World War II who strove to export Marxist-Leninist revolution, condemning the world to decades of cold war.
The return of the hardliners
So too with Iran. After Khomeini's death in 1989, the pragmatic Ali Akbar Hashemi-Rafsanjani became president, followed by the reform-minded Mohammad Khatami. But the hardliners struck back. When Khatami's reform programme was ineffective, Mahmoud Ahmadinejad, an obscure officer of the Basij militia, was elected mayor of Tehran in 2003 (after just 12% of the city's voters turned out), and then defeated Rafsanjani in 2005 to become president.
Ahmadinejad, a fanatical devotee of Khomeini, the revolution's first imam, was a reminder of the revolution's populist inception. To promote an aggressive nuclear policy was to vindicate Khomeini's battle against America, "the Great Satan". Only when Iran's voters lost patience with Ahmadinejad's incompetence and elected Hassan Rouhani in 2013 could the Islamic Revolution be said to be over.
Could America have avoided the waste of the Ahmadinejad years? His predecessors had made serious efforts to improve relations with the US. Encouraged by the victory of the US-led coalition in the 1991 Gulf War against Iraq (the Islamic Republic's arch-enemy), in 1995 Rafsanjani sent very clear signals to the US of a willingness to restore diplomatic ties. The Clinton administration ignored Rafsanjani's effort, and the following year, the US Congress unanimously passed the Iran and Libya Sanctions Act.
Admittedly, Bill Clinton and his advisers had plenty of reasons for scepticism. Rafsanjani was at least partly hostage to hard-line opponents keen to sabotage his foreign-policy initiatives with precisely timed acts of terror in France, Germany and Argentina.
Khatami's "dialogue of civilisations"
But Clinton and his secretary of state, Madeleine Albright, took seriously the proposal by Khatami, Rafsanjani's successor, at the UN General Assembly in 2000 for a "dialogue of civilisations" to open what he called "a crack in the wall of mistrust" between Iran and the US. Sadly, Iran's Supreme Leader, Ayatollah Ali Khamenei, forced his president and foreign minister to avoid the planned handshakes with their American counterparts.
Worse was to follow for those hoping for better US-Iran relations. First, there was Bush's "axis of evil" speech in 2002. Then, in February 2005, just as the hard-line Ahmadinejad was about to begin his first term as president, Bush formally rejected a nuclear deal that had been painstakingly negotiated by Rouhani (then Khamenei's representative in Iran's Supreme National Security Council) and signed in late 2004 by France, Germany and Britain.
As Iran scanned the strategic horizon, it seemed obvious that the US had invaded Iraq because Saddam did not have any weapons of mass destruction. This made Ahmadinejad's insistence on Iran's nuclear "rights" popular with the Iranian masses and the middle class alike.
Obama's political legacy
Despite popular disenchantment with the Ahmadinejad era, that sentiment still prevails in Iran. But the nuclear accord reached last month is the product of a different political context: President Barack Obama was eager to make a deal with Iran part of his legacy, and this time, Rouhani, as president, was able to negotiate with the full backing of Khamenei, with whom (unlike Khatami) he has worked closely.
But there is a deeper reason for the success of the nuclear negotiations: Khomeini's Islamic revolution of 1979 has finally ended – and Khamenei knows it. He must also know that the export of Islamic revolution from Shia Iran has lost its allure, replaced in the Sunni world first by the global jihad of al-Qaida and now by the so-called "Islamic State" and caliphate of Abu Bakr al-Baghdadi.
For Iran, what counts now is no longer ideology but national interest and realpolitik. That is why it finds itself currently backing the opponents of revolutionary Islam: Bashar al-Assad against the Islamists in Syria and the Houthis against al-Qaida in Yemen. And it is why it finds itself not only signing a nuclear accord with the Great Satan but also tacitly co-operating with it against the Islamic State, their common enemy. Now that the revolution is over, co-operation in other areas is likely to become equally appealing.
Said Amir Arjomand
© Project Syndicate 2015
Said Amir Arjomand, the founder of the Association for the Study of Persianate Societies, is Professor of Sociology and Director of the Stony Brook Institute for Global Studies at the State University of New York at Stony Brook.