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 initiated an antitrust investigation into Google, primarily targeting the Android operating system. This could be a strategic warning to Washington amidst ongoing trade tensions. The investigation is also focused on removing restrictions imposed on Chinese smartphone makers.

The Chinese government's move to open an antitrust probe into Google is the latest development in a long and tangled relationship that goes back to the early 2000s. The investigation was one of a flurry of Chinese retaliatory measures announced Tuesday in response to a 10% tariff imposed by U.