China on Friday imposed tariffs on U.S. imports of an acid widely used in food, feed, pesticides and medical fields, amid heightened bilateral trade tensions with Washington.

The Commerce Ministry said in a statement that it would impose a 43.5% tariff on propionic acid imports from the United States starting on Saturday, after an investigation in July found “significant harm” to China’s domestic propionic acid industry.

Despite recent diplomatic visits, the trade dispute between the world’s two largest economies continues to intensify.

In the latest attack, the United States has threatened to raise tariffs on Chinese steel imports and pressured Mexico to ban China from indirectly selling its metal products to the United States.

China’s Ministry of Commerce said on Thursday that it firmly opposes the U.S.’s imposition of additional tariffs and will take all necessary measures to safeguard its rights and interests.