Apple has announced that Sabih Khan, the company’s vice president of operations, will take over for Jeff Williams as chief operating officer later this month. In an announcement on Tuesday, Apple said the move is part of a “long-planned succession” that has Williams retiring at the end of this year.

Williams, who oversaw the introduction of the iPod and iPhone, as well as the Apple Watch, was appointed  COO in 2015. He had been seen as a potential successor to CEO Tim Cook and was called “Tim Cook’s Tim Cook.” Other possible candidates within Apple reportedly include hardware engineering chief John Ternus and software engineering leader Craig Ferighi.

Later this month, Khan will take over the role of COO, while Williams will continue to oversee design and Apple’s health initiative until he retires. In March, Bloomberg reported that Williams is “heavily involved” in a plan to revamp the Health app with an AI-powered health coach that’s rumored to launch next year.

The design team, which has been reporting to Williams following the departure of Apple designer Evans Hankey in 2023, will begin reporting directly to Apple CEO Tim Cook later this year after Williams retires, according to Apple’s press release.

Khan has worked at Apple for 30 years and became VP of operations in 2019. He’s been leading Apple’s global supply chain that produces more than 200 million iPhones every year, and now faces new challenges as Trump and China square off in a trade war.

Williams joined Apple in 1998, where he helped build out the company’s supply chain and “led the effort on Apple Watch over a decade ago and architected the company’s health strategy,” according to the press release.

In the press release, Williams writes, “Working with all of the amazing people at this company has been a privilege of a lifetime, and I can’t thank Tim enough for the opportunity, his inspirational leadership, and our friendship over the years… June marked my 27th anniversary with Apple, and my 40th in the industry. Beginning next year, I plan to spend more time with friends and family, including five grandchildren and counting.”

Update, July 8th: Added more details about the transition.