The state of religious freedom in Iran is not good—Freedom House ranks it “not free,” with nearly the lowest rating, in its annual report. (That’s still enough to best Saudi Arabia, which Freedom Houses places in the “worst of the worst.”) In addition to Sunnis, there are several smaller non-Muslims groups, notably Bahais, Jews, Christians, and Zoroastrians. Compared to them, Sunnis have greater legal protections. Sunni schools of Islamic jurisprudence are officially recognized in the constitution as sources of family law and religious education. Sunnis can serve in the parliament, though they’re not afforded the few reserved seats given to other religious minorities.

In practice, however, the status of Sunnis appears more precarious. As of the end of 2015, the State Department said there were hundreds of religious minorities, including Sunnis, imprisoned. Sunnis complain that though there are an estimated 1 million of them in Tehran, there are no Sunni mosques in the capital. In addition, the State Department noted in its most recent annual religious-freedom report that religious readers had said Sunni literature and teachings were banned in public schools, and new construction of Sunni mosques and schools was banned. Also:

There were reports of arrests and harassment of Sunnis. The International Campaign for Human Rights in Iran (ICHRI) cited activist reports that authorities in Ahvaz arrested 20 Arab-Iranians February 26 for converting from Shia Islam to Sunni Islam, arresting them in a house raid without a warrant and then detaining them in an MOIS office. Mohammad Kayvan Karimi, Amjad Salehi, and Omid Payvand were sentenced to death May 4 on charges of “enmity against God through spreading propaganda against the system.” According to Human Rights Activists News Agency (HRANA), the three were active in preaching Sunni Islam.

In addition, Iranian Sunnis reported raids on worship sites, and being prevented from celebrating Eid al-Adha in 2014. Last summer, clandestine worship spaces for Sunnis in Tehran were reportedly destroyed.

One way that Sunnis—as well as disaffected non-Sunni members of Iranian society—have responded to this environment is to embrace Salafism, hardline Sunni orthodoxy, according to Mehdi Khalaji, a fellow at the Washington Institute for Near East Policy. The Internet has allowed Salafis to spread their ideas and create networks throughout the country. “This is one of the reasons why the regime does not allow Sunnis to build mosques in Tehran or other large cities—it is deeply concerned about Salafis using them to recruit young Shiites who are frustrated with the Islamic Republic’s ideology,” Khalaji wrote in 2013. They also often have ties to Iran’s regional foes, especially Saudi Arabia. “Given these factors and the increasing resentment among Iran’s Arab, Kurdish, and Baluch population, the growth of Salafism is a clear security threat to the regime.”