Twenty five years ago, I was strolling down Leningrad’s main drag, Nevsky Prospekt, with a clutch of other American undergraduates who had recently arrived for two months of intensive language study when Professor Edna Andrews dashed up to us with the news. “They’re shooting them,” she said (or something like it—who can trust a 25-year-old memory of a speech fragment?) with obvious agitation. “They’re shooting the students in Tiananmen Square!”

Had Edna not given us that news, we probably wouldn’t have heard it, or at least not until we got home. In 1989, glasnost’ had already come to the USSR, but that didn’t mean speech was free. State newspapers were still the only ones around, at least for those of us without connections to the world of samizdat. Some of those newspapers were more informative than others, but the limits of political conversation were still clearly proscribed. The Internet didn’t exist, and international calls could only be made by appointment from state-run locations with plastic phones in cubicle-like spaces and who-knows who listening while you talked. Trustworthy information still only trickled through a public sphere mostly bifurcated between propaganda and silence.

What’s striking to me in retrospect is how differently things could have turned out in both countries. When she gave us the news about Tiananmen, Edna was surely agitated because it involved students like the ones she taught being slaughtered. I suspect she was also distressed, though, because at the time it was still easy to imagine something similar happening in the USSR, perhaps even to people she knew personally.

In 1989, politics had already started to move in the Soviet Union, but neither democratization nor disintegration was a foregone conclusion. That spring, citizens had picked delegates to the inaugural session of the Congress of People’s Deputies in elections that were, at the time, the freest the USSR had ever held. The new Congress’ sessions were shown on live television, and their content was stunning. “Deputies from around the country railed against every scandal and shortcoming of the Soviet system that could be identified,” Thomas Skallerup and James P. Nichol describe in their chapter for the Library of Congress’ Russia country study. “Speakers spared neither Gorbachev, the KGB, nor the military.”

But the outspokenness of those reformist deputies belied their formal power. More than 80 percent of the Congress’ deputies were Communist Party members, and the new legislative body the deputies elected that summer, the Supreme Soviet of the USSR, was stuffed with “old-style party apparatchiks.” Two years later, reactionaries inside the government mounted a coup attempt in which President Gorbachev was arrested and detained for a few days and tanks were deployed on the streets of Moscow.

Tank near Red Square on 19 August 1991. © Anatoly Sapronyenkov/AFP/Getty Images

That August Putsch looks a bit clowny with hindsight, but it didn’t have to fail. Likewise, the brutal suppression of China’s 1989 uprising didn’t have to happen, or to succeed when it did. In a story published this week in the New York Times, Andrew Jacobs and Chris Buckley describe the uncertainty of Chinese policy toward the uprising and the disunity of the armed forces tasked with executing it—and, eventually, the protesters in Tiananmen Square.

“At the time,” Jacobs and Buckley write, “few in the military wanted to take direct responsibility for the decision to fire on civilians. Even as troops pressed into Beijing, they were given vague, confusing instructions about what to do, and some commanders sought reassurances that they would not be required to shoot.” Seven senior commanders signed a petition calling on political leaders to withdraw the troops. Those leaders responded by disconnecting many of the special phones those commanders used to communicate with each other. When troops were finally given orders to retake the square “at any cost,” some commanders ignored them. At least one pretended that his battalion’s radio had malfunctioned.

As Erica Chenoweth and Maria Stephan show in their study of civil resistance, nonviolent uprisings are much more likely to succeed when they prompt defections by security forces. The Tiananmen uprising was crushed, but history could have slipped in many other directions. And it still can.