The most striking thing about Sayfullo Saipov, the 29-year-old Uzbek man who allegedly drove a pickup truck into a crowd in Lower Manhattan, killing eight people, was his big, black, bushy beard: He wouldn’t have been able to grow one in his native Uzbekistan.

A beard would be considered a sign of religious extremism in Uzbekistan, which has a long and notorious record of restricting the religious practices of its majority Muslim population. All clerics are government vetted; all madrassas are government controlled and infiltrated by undercover informants. Pilgrims to Mecca have to go through a rigorous government vetting process and are then accompanied on the journey by government minders. The communal marking of the end of each day of fasting during the month of Ramadan is banned, as is the celebration of Eid al Fitr, the feast marking the end of Ramadan. Until recently, children under 18 were banned from attending mosques. The authoritarian regime of Islam Karimov, Uzbekistan’s post-Soviet ruler who died last year, outlawed Islamist political parties and imprisoned and tortured dozens of religious activists. The government keeps a “black list” of people it has decided are religious extremists. According to a recent report by Human Rights Watch, “Those on the list are barred from obtaining various jobs and travel, and must report regularly for police interrogations.” Until the new president shortened the list in August, it contained some 18,000 names.

The ostensible point of all these restrictions was to fight the Islamic Movement of Uzbekistan, or IMU, a jihadist movement that emerged just after the collapse of the Soviet Union—Uzbekistan was, until 1991, a Soviet republic. The IMU wanted to impose Islamic law in Uzbekistan, and was quickly banned by the new Karimov government. IMU fighters scattered throughout the region—to Tajikistan, Afghanistan, and, after the U.S.-led invasion of  Afghanistan in 2001, to the tribal areas of Pakistan—from where they have launched multiple raids into Uzbekistan and Tajikistan. In 2014, the IMU pledged its allegiance to ISIS.

And yet the draconian measures implemented by the Karimov regime have not solved the problem of Islamist extremism in Uzbekistan. They have only pushed problem underground and, ultimately, abroad. Saipov isn’t the first native Uzbek to have been implicated in a terrorist attack. Last summer’s airport bombing in Istanbul was carried out by an Uzbek man, along with co-conspirators from other Central Asian countries. An Uzbek drove a truck into a crowd in Stockholm in April. Last week, an Uzbek was sentenced to 15 years in prison by a New York court for providing material support to ISIS. Uzbekistan has provided some 1,500 soldiers to ISIS in Iraq and Syria, according to the Soufan Group. ISIS has claimed that Uzbeks were responsible for some of its most high-profile suicide bombings in Iraq. In November 2014, the largest Uzbek faction fighting in Syria pledged its allegiance to the Taliban.

In 2014, seemingly acknowledging that government restrictions on the practice of Islam weren’t working, Karimov asked Russia’s Vladimir Putin for help in dealing with his extremist problem. Putin shared Karimov’s concerns, but he was in the process of exporting his own Islamist threat to Syria, turning a blind eye to thousands of Russian citizens going to join the fighting as long as they stayed out of the way during the 2014 Sochi Olympics. This year, Russia has overtaken Saudi Arabia and Tunisia to become the largest supplier of foreign fighters to ISIS. Men from Russia’s Muslim republic of Dagestan told me in April that when they ventured into ISIS-controlled territory in Syria, they found a Russian-language subculture on the streets of cities like Tabqa, where fighters and families from all over Central Asia were united by that region’s Soviet lingua franca. On the Syrian border with Turkey, they encountered busloads of Central Asian women—mothers going to wrest their children from the clutches of the Islamic State.

Now, as ISIS continues to lose territory, those Russian-speaking fighters from Uzbekistan and other post-Soviet countries are scattering. And though there’s so far no evidence that Saipov ever traveled to Syria to train, he didn’t have to. There is plenty of extremist material online, and vehicular attacks like the one in New York—and in Stockholm, Berlin, and Nice—require no particular expertise with weapons, which explains both why they are so hard to prevent and why ISIS actively encourages them. It also suggests that the Islamic State may come to rely on such attacks more as their territory shrinks, and with it, their capacity to coordinate more sophisticated attacks.

Consider this: The bomber who detonated himself in the St. Petersburg metro in April, killing over a dozen people, was an ethnic Uzbek from Kyrgyzstan. He had never trained in Syria or Iraq, but he had been in touch with his countrymen who had been.

It’s not yet clear where Saipov was radicalized; an acquaintance of his has speculated  it didn’t happen until after he moved to the United States. Saipov’s Uzbek roots, however, highlight the complex interplay of factors that go into an individual’s radicalization. In Uzbekistan, as it has been noted, Islamist extremism is often a stand-in for anti-authoritarianism and discontent with the violence and corruption of the Karimov clan. It also indicates that the authoritarian environments of the post-Soviet states— Uzbekistan in particular—have proven that cracking down on religious practice and ideology are ineffective. The measures not only fail to stop extremism, they seem to be its chief incubators. And with no caliphate to travel to, the extremism born in places like Uzbekistan will find other places to spread.