While China’s Communist Party has long punished people seen as threats to its rule, government authorities under Chinese leader Xi Jinping have engaged in the most relentless pursuit of dissenters since the crackdown on the 1989 Tiananmen Square pro-democracy protests, according to academics and activists.

“Over the past eight years under Xi, authorities have become hypersensitive to the publicizing of protests, social movements and mass resistance,” said Wu Qiang, a former politics lecturer at Beijing’s Tsinghua University…

Mr. Xi’s crackdown has snared women planning protests against sexual harassment, human-rights lawyers once given leeway and Marxist students advocating workers’ rights. Many have endured lengthy detentions and various forms of psychological pressure.

“Their goal is to make you feel helpless, hopeless, devoid of any support, and break you down so you begin to see activism as something foolish that doesn’t benefit anyone, and gives pain to everyone around you,” said Yaxue Cao, a Washington-based activist who runs China Change, a news and commentary website advocating for human rights. “In so many cases, they are successful.”