Popular protests in China, feminist revolt in Iran, antiwar activism and possible sabotage in Russia—could the world’s three largest oppressive countries be teetering toward revolution or serious reform?

It wouldn’t be the first time. All three underwent multiple revolutions in the 20th century: Iran in 1906 (parliamentary) and 1979 (Islamist); China in 1911 (republican) and 1949 (Communist); Russia in 1905 (constitutional), 1917 (Bolshevik), and 1991 (quasi-democratic imperial-breakup).

All those upheavals came as surprises. So, even though revolutions in those countries seems unlikely today, they’re not impossible—and the people in those countries, both the aspiring revolutionaries and those defending the present order, know this. They know that popular uprisings once took place in those countries. And this  awareness heightens tensions when they’re allowed to simmer and then boil.