BEIJING — A popular news anchor watched by hundreds of millions of Chinese poured scorn on the United States, using an obscenity to accuse it of sowing chaos. A prominent official blamed Washington directly for the antigovernment protests upending Hong Kong.

Pointed hostility toward America, voiced by Chinese officials and state-run news organizations under the control of an all-powerful propaganda department, has escalated in recent weeks in tandem with two of China’s big problems: a slowing economy complicated by trade tensions and turbulence in Hong Kong that has no end in sight.

“It is, after all, the work of the United States,” Hua Chunying, spokeswoman for the Ministry of Foreign Affairs, said this week of the unrest in Hong Kong. Like other Chinese officials, she presented no evidence of American involvement in the demonstrations, which stem from worries over Beijing’s encroaching influence in the semiautonomous region.

This is hardly the first time China has responded to domestic problems with frontal assaults on outsiders. Thirty years ago, Washington was accused of fomenting the pro-democracy upheavals on Tiananmen Square.