GOVERNMENTS CRUMBLE AND EMPIRES FALL in all kinds of ways. A relentless army of insurgents can overwhelm a national military, as we saw in Afghanistan this week. A shocking act of protest can set off a chain reaction, as when a Tunisian street vendor lit himself on fire in December of 2010, leading to the “Arab Spring” uprisings of 2011 across the Middle East. Massive popular demonstrations can force the end of repressive control, as we saw when the Berlin Wall came down in 1989 and when the Soviet Union finally dissolved two years later.

These are exceptions to the rule; for long historical stretches, the continuity of power can seem impossible to break. The demonstrations in Beijing’s Tiananmen Square were crushed in June of 1989. Widespread protests in Hong Kong failed in recent years to moderate China’s attempts to tighten control of the former British colony. The Chinese Communist Party has expressed a deep fear of ethnic separatism, and leaders have doubled down on measures to prevent Xinjiang, Tibet, and Hong Kong from demanding increased autonomy or independence, even in the face of widespread criticism from the West.

The United States sometimes seems as resistant to structural change as China. From the first days of the Trump administration, this nation witnessed some of its largest street protests ever—the Women’s Marches on January 21, 2017, attracted more than four million people spread through at least six hundred cities. Only a year ago in May and June, weeks of sustained protests over the killing of George Floyd in Minneapolis, Minnesota, were estimated to have drawn between fifteen and twenty-six million Americans to rallies and marches. None of it seemed to have made an immediate difference in cracking the minority-rule grip of elected Republicans in state and federal office or weakening Trump’s retrogressive agenda during his four-year term. Nor were the hundreds of deluded insurrectionists who descended on Washington on January 6 able to prevent Joe Biden from being certified as the new president.

Yet, in recent years, progressives and conservatives alike came to believe a coup of some sort could happen in the United States. Some of the most unhinged elements on the far right apparently still think one is imminent: this is the month Trump was to be reinstated in the White House, after “evidence” would emerge to prove he was the rightful winner of the 2020 election. Normally, though, strong military support is necessary for a successful coup d’état. And even then, things can fall apart. It was thirty years ago today that the “August coup” in Moscow was stopped in its tracks by angry protests in the streets. The people of Moscow rejected the coup attempt—engineered by disgruntled Communist Party members in league with the Soviet Armed Forces and the KGB. The hardliners wanted to end the liberalizing reforms of the USSR’s president, Mikhail Gorbachev. Tens of thousands of protesters swarmed the streets of the capital, and the coup failed after pro-democracy demonstrators physically blocked troops from seizing control of the Soviet White House, the parliament building of the USSR. The coup attempt was the last gasp of the old order. By the end of the year, communism had collapsed in Eastern Europe, and the Soviet Union ceased to exist as a political entity.

Every generation sees windows open and close. There is no historical pattern that tells us whether widespread protest will carry the day, or when military force will prevail, or whether governments that seem unshakable will fall. It may seem a safe assumption that the United States is not nearly as unstable as the Soviet Union was in 1991. Yet during these years of deep anger at a system that is failing to take the basic needs of the people into account, we’ve seen how weak our democratic norms and institutions really are. Even if a military coup here is unimaginable, the hijacking of the next presidential election is not. Could it be stopped by massive demonstrations in the streets? The history of those tumultuous years in Eastern Europe during the late 1980s and early 1990s speak directly to us now, offering both high hopes and dire warnings. Because I spent time in 2014 studying history in Berlin, that moment in 1989 when history took a sudden U-turn kept coming back to me during the Trump years. Those events remind us that decisive political moments are rarely expected, and even more rarely planned. Governments change all the time. But every once in a while, empires fall.