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.

China's antitrust investigation into Google, which does not offer most of its consumer-facing services including search and email in the country, seems to make little sense on the surface, but analysts said the move could be seen as a warning shot to the US and a threat to the Android operating system.