Trade teams from China and the United States continue to talk and will meet in September, but tariff increases on Chinese goods set to go in place on Sunday will not be delayed, President Donald Trump said Friday.

The U.S. president, who has alternated between expressing optimism about a trade deal and criticism of China for its economic policies, also said he thought the trade talks had led Beijing to be more restrained in its response to demonstrations in Hong Kong.

A tit-for-tat tariff war between the world's two largest economies now involves hundreds of billions of dollars of each country's goods and threatens global economic growth. Uncertainty about when or how the dispute could end has roiled markets and complicated corporations' long-term investment plans.