The 1999 protests at Tehran University are particularly significant, though, because at the time the country’s president, Mohammad Khatami, championed the kinds of reforms the students demanded. He had been elected two years earlier promising a freer press and an end to repression. He publicly pleaded with his own government to spare the students in the raids. Yet in the end, he could do nothing to save them.

It’s also worth looking at who was on the pro-regime side of the uprising. Leading a counter-demonstration was the secretary of Iran’s national security council, Hassan Rouhani. A relatively unknown cleric at the time, he told his supporters that the students demanding reform were “enemies of the state.” This was no idle threat. A student shot dead by security forces was later found guilty by a revolutionary court for engaging in unlawful protest. Rouhani, of course, is Iran’s president today. The Obama administration, which relied on him to negotiate the 2015 nuclear deal, touted him as an Iranian moderate. It’s telling that in 1999, he was the face of a regime undermining Iran’s only reformist president since the 1979 revolution.

Khatami’s failure to protect the students is one reason that so many Iranian activists who believed for years in the prospect of incremental reform now feel that radical change the only path forward.