The WSJ reports that China has opened an antitrust investigation into the acquisition of Uber China by local rival Didi Chuxing. The deal went ahead a few months after Apple invested $1B in Didi Chuxing.

The Chinese government has requested details of the deal, together with an explanation for why Didi Chuxing failed to apply for an antitrust review before proceeding. The company had earlier said that it did not believe Uber China’s revenue was high enough to require this.

China’s Ministry of Commerce said Friday it has opened an investigation into Didi Chuxing Technology Co.’s acquisition of Uber Technologies Inc.’s China business, after it received questions over whether the ride-hailing deal complied with the nation’s antitrust law.

Apple said at the time of its investment that it was for strategic as well as investment reasons. It has been speculated that Apple’s car project may be geared towards autonomous ride-hailing services.