Since the inception of the Islamic Republic of Iran in 1978, Tehran has perceived “regime change” in Iran as the US establishment's ultimate aim. The country's strong mistrust of the US also has its roots in two factors. First, as the Iranian sociologist Ahmad Ashraf maintains, Iranian culture in all walks of life relies on conspiracy theories as a basic mode of understanding politics. Second, there are historical facts that reinforce this perception, which include US support for Iraqi dictator Saddam Hussein during his eight-year invasion (1980-1988) of Iran, former US president George W. Bush's doctrine of including Iran in the “axis of evil”, the articulation of an “all options on the table” mantra in dealing with Iran's nuclear programme, US support for the Iranian opposition in its attempts to destabilise the regime, the imposition of paralysing sanctions and covert operations in Iran. A glaring example of US efforts to destabilise the regime occurred in 2009 when the Americans were trying to exploit the massive upheaval in Iran that emerged under the banner of the Green Movement. In the aftermath of the street protests in Iran, the then US secretary of state Hillary Clinton said, “Behind the scenes, we were doing a lot … to really empower the protestors.” Despite the high level of mistrust this history has given rise to, in an unprecedented statement in early April this year Iran's supreme leader Ayatollah Khamenei suggested that a nuclear deal could lead “to negotiations with [the United States] about other issues.” One theory maintains that if such further negotiations were to occur, the Iranian government could ease restrictions on the press and free speech due to its perception of a diminishing threat from the United States, Tehran's fundamental concern. After all, it is important for the government to repair its legitimacy, which was badly damaged during the violent crackdowns on street protesters in 2009. This perspective, however, may be flawed for several reasons. As the Iranian sociologist Ramin Jahanbegloo puts it, there has long been a fragmentation in Iran that has resulted in tensions between tradition and modernity. From 1920 to 1978, the modernists were in power. The two shahs from the Pahlavi Dynasty relentlessly pursued a modernisation project in Iran, attempting to “Westernise” the country while oppressing and marginalising the traditionalists and religious conservatives. Mohamed Reza Pahlavi, Iran's last shah before the Islamic Revolution, referred to the religious conservatives as erteja-e siah (black reactionaries), a derogatory term. To resist these policies, an Islamic movement under the leadership of Ayatollah Khomeini emerged. The movement led to the 1978 Islamic Revolution that shifted power from the modernists to the traditionalists, who have maintained authority in the country ever since. Understanding the social and political structure of Iranian society is of paramount importance. Missing this can lead to significantly false analyses, where, for example, movements of dissent in Iran are viewed simply as people against the regime. Dissent should instead be viewed as a struggle between two camps: the religious conservatives (traditionalists) and the modernists, which include supporters of liberal Islam and secularists. Iran's 2009 contested presidential elections are a case in point of this tension. According to a report on a now-banned website of the reformist candidate in the elections, Mir Hossein Mousavi, defeated by the hardliner Mahmoud Ahmadinejad, legitimate polling numbers showed Mousavi with 21.3 million votes versus Ahmadinejad's 10.5 million. Taking these figures at face value, which could for obvious reasons be biased in favour of Mousavi, the conservative power elite that rules Iran, at the time represented by Ahmadinejad, had at least 10 million supporters. The elections were rigged, but while it is important to note that the street demonstrators represented a large portion of the population, the regime also enjoyed considerable support from the conservatives. These two factions, both within and outside the political system and regardless of the US threat, are engaged in a constant power struggle. A receding US threat will not ease this ancient battle. It may surprise some that détente with the US could exacerbate freedom of speech conditions even further in Iran. It is true that the Iranian leadership welcomes less tension with and less of a threat of regime change from the US, as Khamenei's reconciliatory statement suggests. However, he and like-minded conservatives still have serious concerns about normalising relations with America. “Cultural invasion”, or tahajome farhangi, as Ayatollah Khamenei puts it, is a major factor of concern among conservatives. They resist liberal moral and social values, most importantly the separation of religion and state. Meanwhile, they believe that the US deliberately promotes liberal values among Iranian young people, both to erode their religious beliefs and to ultimately undermine the influence of the Islamic system. The Iranian ruling elite continually reiterates that numerous Farsi television stations, primarily in the US, are directly or indirectly sponsored by the US government as major channels of cultural invasion towards Iranian society and in order to promote sexual freedom, the consumption of alcohol and immodesty. The signature of a nuclear deal and the removal of sanctions, even without any US involvement in regime change, would most likely result in an explosion of tourism between the two countries and the expansion of trade and commerce with the West. Conservatives might believe that these exchanges could result in the rise of “westoxificated” urbanites and technocrats as a notable force in Iranian society. Such an outcome could potentially threaten the nezam (political system) in Iran. Not only could it weaken people's religious beliefs and lead to the rise of liberals and technocrats, but it could also leave conservative grassroots supporters disappointed, who might then withdraw their support for the establishment. These likely consequences of a nuclear deal may lead to conservatives feeling even more threatened by their opponents inside Iran. They may be nervous and react by tightening, rather than loosening, restrictions on freedom of the press and expression. The experience of former Iranian president Mohamed Khatami's time in power gives a picture of the way conservatives may react when threatened by their opponents, in this case the supporters of social and political liberties. The early years of Khatami's presidency, from 1997 to 2005, gave rise to an unprecedented explosion in newspapers, political liberalisation and the expansion of the freedom of press. In 2000, liberals and supporters of Khatami wrested control of parliament from conservatives for the first time since the revolution. The reformists gained control over the executive and legislative branches of the government. However, the police and judiciary remained under conservative control. The conservatives grew nervous and attacked the reformists as a result. Nineteen newspapers were closed by court order, and several prominent reformist journalists were arrested over a six-year period. Cleric Abdullah Nouri, an associate of Khatami and vice-president, was found guilty on 15 counts, including for activities against the system, and sentenced to five years in prison. The strongholds of the conservative school of thought are deeply entrenched in Iran. Among them are the supreme leader Ayatollah Khamenei, the Iranian Revolutionary Guards Corps (IRGC), the large paramilitary Basij militia (which works under the supervision of the IRGC), the police forces, and the perennially conservative judiciary. Indeed, Ayatollah Sadeq Larijani, the current head of the judiciary, has been put forward to succeed Ayatollah Khamenei. The writer is a political analyst writing primarily about Iranian affairs and co-author of Iran and the United States: An Insider's View on the Failed Past and the Road to Peace.