The deal to regulate Iran’s nuclear program is a significant political success for the Iranian regime. It will dramatically ease sanctions against the country, and gradually allow Iran access to some $100 billion in frozen financial assets. And, it demonstrates the Iranian regime’s ability to successfully negotiate a long, complicated, and fraught process with Western powers and arrive at a relatively favorable result. Yet, the deal imposes an acute dilemma on the regime.

The deal presents Iran with a historic opportunity to alter its regional and international positioning of the last thirty-five years. Iran can now initiate a dialogue with the West with the objective of arriving at a new relationship between the two whereby their interests in the region do not collide.

The case is strong on both sides. For the West, Sunni militant Islamism is now the primary threat emanating from the Middle East. Iran is the sole Middle Eastern country with the military, intelligence, logistical resources, and, crucially, the willingness to commit ground forces in battles against groups such as Jabhat Al-Nusra, the Islamic State in Iraq and Syria, and others (and with a record of doing so). Also from a Western perspective, Iran could be a stabilizing force in potentially explosive countries, not only Iraq but also Lebanon.

Economically, Iranian and Western interests could be aligned. Oil contributes less than 40 percent of Iran’s gross domestic product. Reasonably priced oil will not be detrimental to Iran, provided that the country benefits from favorable trade agreements.

A rapprochement does not necessarily fly in the face of Western values. Despite its theological political system, Iran is by far more democratic than almost all Western allies in the Middle East. Plus, Iran is an old, rich, and highly sophisticated civilization; it has the cultural aspects that appeal to, resonate with, and get the respect of the West.

From Iran’s perspective, a rapprochement with the West presents the country with potentially lucrative economic opportunities. In addition to the obvious benefits, this will be of high value to the regime. The current Iranian president, Hassan Rouhani, has managed to absorb some of the anger that his predecessor, Mahmoud Ahmadinejad, had stirred among wide groups of the country’s upper middle class. And yet, many Iranian strategists know that the dissatisfaction that young compatriots have with the regime has not subsided. They remember that only six years ago, Tehran witnessed major demonstrations that seemed the seed of an uprising. Significant economic improvements could be highly beneficial to the stability of the Islamic Republic, especially given the looming moment of transition, as Supreme Leader Ayatollah Ali Khamenei, 76, leaves the scene.

Strategically, a rapprochement with the West would inevitably lessen the importance of the West’s (and especially America’s) alliance with the Gulf states. This would give Iran a much wider manuevering space in the Gulf and the eastern Mediterranean. Also from the Iranian perspective, there are soft factors that make such a rapprochement appealing. Like all old nations with illustrious histories, Iran craves respect, not from the countries it sees as lesser, “nouveau riche” ones, but from those it deems its peers, the big Western nations.

Despite all of these reasons, a rapprochement with the West would pose an excruciating dilemma for the regime. Iran’s 1979 revolution, the legitimacy basis and anchor for the current regime, was more than a populist uprising against an oppressive king, Shah Mohammad Reza Pahlavi. Despite its different constituents, the revolution quickly gave rise to a colossal social movement that came under the overarching umbrella of the political project that Ayatollah Khomeini had envisaged. This project was not particularly focused on the shah; Khomeini was also equally indifferent toward the wants of his people; he was almost dismissive of the social and economic needs that many observers believed were the real triggers of the Iranian revolution. For Khomeini, the shah was a minor figure in a “corrupt global power structure” led by the United States (“the Great Satan”) and perpetuated by “the sinful West.” In his view, the revolution was a religious wave emanating from the heartland of Islamic Shiism, heralding a return to Islamic rule as he understood—and defined—it. That wave was supposed to reach Shiite-majority Iraq, the entire Gulf, and to extend to parts of the eastern Mediterranean, the home of large Shiite communities. And for a moment, in the early 1980s, Khomeini even thought that his Islamic model could transcend Shiite Islam and inspire new thinking in major Sunni Muslim countries such as Egypt, one that could inspire other Islamic revolutions. Khomeini’s project was not about local or regional politics. He believed he was resuscitating the one true form of governance anchored on the one true legitimacy, the one mandated by God.

Khomeini also shunned Persianness. For him, Iran was first and foremost an Islamic country. Its specific cultural features (language, arts, crafts, cuisine, and crucially Iranians’ veneration of their rich history) were at best marginal ornaments around the country’s defining identity: Islamism, at worst falls into sinfulness that ought to be corrected. Focusing on Islamism and eschewing Persianness gradually led to a distorted view of Iran’s history and regional positioning: undermining the cultural factors that underpinned its centuries-old intellectual hegemony over its immediate neighborhood and accentuating its religious and ideological worldview.

In this view, the Islamic Republic’s support for groups such as Hezbollah and Hamas, stance against the United States and Israel, condescension toward modern Western modes of thinking and lifestyles, and antagonism against the Arab monarchies of the Gulf, do not just stem from political calculations or strategic objectives and interests. They are rooted in the intellectual foundations upon which the current Iranian political structure was built.

Though some Iranian leaders in the last two decades have tried to instill in the Islamic Republic a more humanistic social contract and worldview, none has ever sought to demolish the foundational principles that Khomeini had erected. In different ways, “reformers” such as Mohammad Khatami, Mehdi Karroubi, and Rouhani, have wanted to evolve the system, widen the interpretation of what an “Islamic Republic” means, and solidify the regime’s legitimacy, particularly after it became clear to them that, three decades after the revolution, demographics and social changes were putting strong pressures on the political structure. This means that the division within Iran’s political elite between “hardliners” and “reformers” is not about the nature of the state, its position in the world, and its grand objectives; it is primarily about the permissible degrees of pushing the boundaries that Khomeini had laid down.

A rapprochement with the West and pursuing a new regional positioning for Iran, one in which its interests are aligned with the West’s, would be tantamount to removing the pillars upon which the Islamic Republic has relied for over three decades. Even if the strategic and internal political cases for that shift of strategy and positioning are compelling, it would take a totally different worldview and a dramatically charismatic set of leaders to affect that change. None of these factors exist today within the Iranian leadership.

Such a shift would also be very painful. The vast majority of this generation of Iranian leaders look to Khomeini as more than just a revolutionary leader who created the regime they preside over. For them, Khomeini was the man who rejuvenated Shiite Islamism after at least two centuries of political and social marginalization. He was the man who came to represent the will and aspirations of tens of millions of Shiites, in and outside Iran. To the Islamic Republic of Iran, Khomeini is not the country’s George Washington but the Iranian Saint Peter. Casting aside his views as obsolete and deviating from his legacy and policies would transcend the realm of political and strategic thinking. For many influential Iranian decision-makers this would be tantamount to betraying their own faith, what they sincerely believe is God’s will.

Iran’s classic mercantile mentality could prevail. Many Iranian decision-makers might try to leverage the opportunities that the deal offers, without deviating from the “righteous path” they believe Khomeini put them on. That will mean taking half measures: cooperating with the West in Iraq and Afghanistan, against militant Sunni Islamism, and in some trade agreements, while at the same time continuing to support “resistance groups” such as Hezbollah and Hamas and projecting Iran as a regional Shiite power. As it happens in the bazaars of Shiraz and Esfahan, half measures conclude some transactions; traders return home quite happy with the day’s profits. But half measures hardly make a mere trader a shabandar: a chief merchant who secures his political legitimacy over trade in a region and thereby acquires colossal wealth and prestige.

It might take a new cadre of leaders in the Iranian political structure to see that Khomeini’s legacy has brought them nowhere. Some might understand that the anger that triggered the 2009 demonstrations remains. And that military and political successes in troubled countries such as Syria, Lebanon, and Iraq do not assuage the frustrations of the groups with the greatest potential in Iranian society.

The deal offers Iran a golden opportunity to evolve, with dignity and huge benefits, from the system that has held it down for the last three decades, and shape a new present and future for its society and for itself in the region. But for that to happen, Iran will have to escape the inhibitions of its taboos. So far, its leaders seem neither willing nor able to do that.

A version of this article originally appeared on July 23, 2015.

Tarek Osman is a political economist focused on the Arab World and is the author of Egypt on the Brink. He was the writer and presenter of the BBC’s 2013 radio series “The Making of the Modern Arab World” and the 2015 radio series “Saudi Arabia: Sands of Time.” He is the political counselor for the Arab World at the European Bank for Reconstruction and Development. On Twitter: @TarekmOsman.