Milan Kovac, who oversaw the development of Tesla’s “Optimus” humanoid robot posted on X that he had made “the most difficult decision of my life” and would be “moving out of my position,” confirming a Bloomberg report from earlier Friday afternoon that he was departing the company.

“I’ve been far away from home for too long, and will need to spend more time with family abroad,” he wrote in the post. “I want to make it clear that this is the only reason, and has absolutely nothing to do with anything else. My support for [Elon Musk] and the team is ironclad—Tesla team forever.”

Musk later replied to the post on X, thanking Kovac for his contributions to the company and saying it had been an “honor” to work with him.

The departure is a meaningful one for Tesla. Musk has repeatedly made public statements staking the future of the company on Tesla’s self-driving software and its yet-to-be-released humanoid robot product. Musk has claimed that the Optimus robot, specifically, could generate “north of $10 trillion in revenue” for Tesla and be its biggest product ever. It’s largely his bullishness on these AI-powered initiatives that have contributed to Tesla’s soaring stock price, which some analysts have argued is divorced from reality. 

Kovac’s departure raises questions over the future direction of Optimus, and whether Tesla will successfully be able to develop, manufacture, and deliver the humanoid robots. Bloomberg reported that Ashok Elluswamy, who leads Tesla’s Autopilot, would be taking over responsibilities for Optimus. Tesla had already been criticized for overselling the capabilities of Optimus after it failed to alert attendees of its “We, Robot” launch event that humans were apparently remotely controlling the robots. (Kovac had confirmed in a social media post after the event that the robots were human-assisted “to some extent”)

The departure of one of Tesla’s top engineers adds to what has already been a troubling week for the electric vehicle maker. Tesla’s shares tumbled this week as President Trump and Musk took to their respective social media platforms to hurl insults at one another. Trump accused Musk of being frustrated that EV credits for Tesla cars would go away as part of the “Big Beautiful Bill,” while Musk accused the president of irresponsible spending with the proposed legislation. The conversation spiraled into insults and even discussions of cutting SpaceX contracts with NASA as the partnership between the two figures very publicly imploded.

Adding to Tesla’s woes, Wall Street investment bank Goldman Sachs issued a note to investors on Thursday forecasting weaker-than-expected sales of Tesla cars in the second quarter.

Tesla shares recovered some ground on Friday as Musk said he was open to making amends with Trump, though the stock still finished the week down 14% from January (still, Tesla shares are trading nearly 66% higher than they were this time last year.)

In his social media post, Kovac recounted how he had joined Tesla in 2016 as an engineer on its Autopilot team and that he had transitioned to lead the Optimus group in early 2022 when Tesla had “nothing but a couple Kuka arms arranged upside-down,” referring to the industrial robotic arms that are often used in automated factory systems.

Tesla did not respond to an immediate request for comment on Kovac’s departure.