China said it was opening an antitrust probe into Google, part of a series of actions Tuesday that also included tariffs on U.S. coal and liquefied natural gas imports as well as restrictions on the export of certain metals.

China has announced a flurry of retaliatory measures against the U.S., including tariffs on imports of products such as coal, liquefied natural gas products and crude oil, as well as an antitrust probe into Google.

China said it had started an antitrust investigation of Google, which works with Chinese companies on smartphones and advertising outside the country.