...China increasingly casts itself not as a fading civilization trying to catch up to the West but as a superpower poised to surpass it. Chinese nationalists and state-linked commentators say they have Mr. Trump to thank. America under his rule, they say, validates Mr. Xi’s worldview centered on “the rise of the East and decline of the West.”

For decades, many Chinese viewed the United States with a mix of admiration, envy and resentment. America represented wealth, technological sophistication and institutional confidence. Even critics of Washington who reviled the American system often assumed that it worked......

In January, a nationalistic Beijing think tank affiliated with Renmin University published a triumphant report about Mr. Trump’s first year back in office. The report argued that his tariffs, attacks on allies, anti-immigration policies and assaults on the American political establishment had inadvertently strengthened China while weakening the United States. Its title: “Thank Trump.”

The report called Mr. Trump an “accelerator of American political decay,” with the United States sliding toward polarization, institutional dysfunction and even “Latin American-style instability.” His hostility toward China, the authors argued, was a “reverse booster” that unified the country and helped bring about its strategic self-reliance.....

But Mr. Trump’s return to office and his administration’s erratic decision-making in both domestic and foreign policy have supplied the propaganda machine with plentiful fresh material. Images of immigration raids, the Minneapolis shootings and bitter political infighting circulate widely on Chinese social media alongside triumphant commentary about American dysfunction. What once sounded to many educated Chinese like exaggerated propaganda increasingly feels, to some, observational.