In late November, a journalist named Ali Pour-Tabatabaie reported that 18 girls from an arts academy in the city of Qom, Iran, had fallen sick, apparently from the effects of poison. The story got little attention at the time, as the country was consumed with the protests that had begun after the death of Mahsa Amini in police custody. The 22-year-old woman had been arrested by the morality police on grounds of not wearing the hijab, or mandatory headscarf, properly. Two weeks after that first report of poisoning, 51 students were hospitalized in Qom. By the end of December, a dozen more cases of suspected mass poisoning of students, most of them female, were reported in states around the country. The timing of these incidents, occurring within weeks of the nationwide anti-regime protests led by women and girls, has raised suspicion for many Iranians that the attacks are a form of retribution for dissent.

The students complained of a variety of symptoms, including dizziness, nausea, shortness of breath, and general weakness, that had come on after they had smelled something foul. What some described as the odor of rotten fruit, and others compared to the smell of bleach, had suddenly filled the air. In the central city of Borujerd, a teacher said she had seen “something like a bomb” tossed into a school compound.

By March, more than 5,000 students, in 25 provinces and from 230 schools, had been affected. The closing of schools last month for the Iranian New Year, Nowruz, raised hopes that the attacks might have ended. But as schools reopened, those hopes were dashed when a series of new cases were reported in several cities.

When the first cases appeared, the authorities tried to downplay the issue. The governor of Qom attributed the incident to a carbon-monoxide leak from schools’ heating systems, but a parliament representative from the principality called it “suspicious.” Some officials accused the country’s foreign enemies, as Iran often does, while others dismissed the event entirely as mass hysteria. Some foreign observers cited by Nature magazine say that a mass psychogenic event brought on by stress reactions to the protest unrest and state violence cannot be ruled out; other experts discount this hypothesis, pointing to the abundant number of cases of hospitalizations of girls suffering physical effects.

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In late February, a health minister said that some of the cases had been caused by chemical poisoning, although that statement was soon rebutted by the interior minister. No specific substance responsible for the symptoms has been identified, but the interior minister recently announced that “suspicious samples” had been recovered during investigations. In mid-March, the United Nations High Commissioner for Human Rights issued a report that called the poisonings “deliberate.” The regime appears to have abandoned its earlier dismissals; by this month, more than 100 suspects had been arrested in connection with the incidents.

The government’s double-talk planted confusion among the public and suggested that there was no consensus among officials. Such contradiction—one official offering an explanation, only to be undermined by another—is characteristic of Tehran’s damage-control tactics. At times, an impression of division can reflect real tensions within the ruling elites. At others, it can be fabricated to project a false sense of behind-the-scenes competition between hawks and doves, as if the elites were somehow responsive to public opinion.

Amid this information mayhem, Iran’s supreme leader, Ali Khamenei, finally broke his silence after three months and offered a statement of his own: “If the poisoning of students is proven, those behind this crime should be sentenced to capital punishment and there will be no amnesty for them.”

The severity of Khamenei’s retributive language did not convince many people that he sincerely intended to investigate the poisonings and identify suspects. In a country that has installed more surveillance devices in public places than George Orwell’s Big Brother could dream of, few believed that the authorities did not already know who the culprits were. Furthermore, the sheer geographical spread of the poisonings made it improbable that anyone without access to state resources could have carried out the attacks. Yet, instead of those behind the crime, the reporter Pour-Tabatabaie was arrested, though his family are uncertain which agency is detaining him and on what charges.

Amid the doubt and fear, speculation abounds. Speaking with the Persian-language service of the BBC, Hatam Ghaderi, a political-science professor in Tehran, called the poisonings “the most blatant example of state-sponsored terrorism, intended to sow fear among people.” Ghaderi suggested that the incidents might be a show of force by the more radical, “Taliban-like” elements within the regime ahead of a power struggle anticipated after the death of the aged and ailing Khamenei. Ghaderi’s argument gains plausibility from the fact that Qom, the epicenter of the poisonings, is known for its religious seminaries and as a stronghold of Shiite clerics. And because even Qom had seen protests in recent months, the poisonings could be retaliation or deterrence aimed at the next generation of young women drawn to reject the hijab. If, in fact, rogue, “Taliban-like” elements are the culprits, or if the public is led to believe that they are, the supreme leader could appear as the lesser of two evils, compared with the utterly ruthless hard-liners who might be maneuvering to replace him.

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Some Iranians nevertheless regard the supreme leader himself as chiefly responsible—not necessarily for directly ordering the poisoning attacks, but for tacitly permitting his conservative supporters to deal with dissent as they see fit. Even before the poisonings of schoolchildren began, the regime has been able to rely on plainclothes agents to carry out physical attacks on protesters; sometimes they include members of the Basij, a volunteer paramilitary organization aligned with the Islamic Revolutionary Guards Corps. Ali Sajjadi, a U.S.-based historian and journalist, believes that Khamenei has effectively incited such vigilantism as far back as June 2017, when he told a group of university students that they should see themselves not merely as “soldiers,” but as “officers” in a “soft war” in defense of the Islamic Republic’s values and beliefs. Elaborating on his bellicose metaphor, he told them that they should “fire at will.”

Those “officers” may have heard Khamenei’s declaration on October 3 that “some protesters only needed a punishment in order to recognize their error” as a call to action. What the punishment should be, and who should deliver it, were matters Khamenei left for others to decide for themselves. Not unlike the mob that broke into the U.S. Capitol on January 6, 2021, the devout followers of the supreme leader were given license to do what they thought he had asked of them.

When suspects were eventually arrested, the leniency shown by officials was striking, compared with the draconian treatment of protesters against the regime—hundreds have been killed in the streets, thousands imprisoned, and several executed. But these poisoning suspects thus far remain unnamed and have not been charged. An interior-ministry deputy spoke of the alleged perpetrators as if they were mere schoolyard pranksters. “Among the detainees are those who are not enemies, and who, with calm and proper guidance, will be managed,” the official said.

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Until now, the Iranian regime had reserved its worst malevolence for dedicated political opponents. Its operatives have hunted down dissidents, including exiles, and assassinated, disappeared, beheaded, kidnapped, or executed them. If, as Ghaderi and others allege, these school poisonings were state-sanctioned, that would represent a new level of indiscriminate regime violence, dire even by Tehran’s standards, against its citizens. No question, the strength of such a sustained and widespread protest movement has made it the greatest domestic challenge to the Islamic Republic since the clerics took power in 1979. This time, as never before, the protesters were calling not for reform, but for regime change—a demand that even the former presidential candidate Mir-Hossein Mousavi, under house arrest in Tehran, echoed in a message earlier this year. (The widely suspected vote-rigging in the 2009 election, when Mousavi ran against the conservative incumbent, Mahmoud Ahmadinejad, is what sparked Iran’s last great popular uprising, the Green Movement.)

The unprecedented calls for change within Iran present the United States with a historic opportunity. For years, many Americans have believed that the U.S. robbed Iran of a democratic future by supporting its last monarch, the Shah. History is now offering America a second chance to keep faith with the nation’s democratic aspiration. With Russia and China, and now possibly Saudi Arabia, as its autocratic allies, the theocratic regime in Tehran is poised to survive its economic woes. China hopes to replace America on the world stage, but for the many millions of Iranians who are yearning for a democratic future, China can offer only more of the dark present in which they already live. The Iranians’ demand for the rule of law creates a space for America to act as no other global leader can: by hearing and answering the call of people for freedom.