"There is no question that self-driving technology is crucial to the future of transportation -- a future in which Uber intends to play an important role," he writes. "Through that lens, the acquisition of Otto made good business sense. But the prospect that a coupe of Waymo employees may have inappropriately solicited other to join Ott, and that they may have potentially left with Google files in their possession, in retrospect raised some hard questions."

Khosrowshahi didn't admit guilt, however, saying he doesn't believe any trade secrets made their way from one company to another. "We are taking steps with Waymo to ensure our Lidar and software represents just our good work."

Waymo's response? That it's going to work with Uber to make sure its data isn't being used with Uber's Advanced Technologies Group. "We are committed to working with Uber to make sure that each company develops its own technology," a spokesperson said. "We have always believed competition should be fueled by innovation in the labs and on the roads, and we look forward to bringing fully self-driving cars to the world."