Apple has announced that Jeff Williams has been named chief operating officer and Johny Srouji is joining Apple’s executive team as senior vice president for Hardware Technologies.

Phil Schiller, senior vice president of Worldwide Marketing, will expand his role to include leadership of the App Store across all Apple platforms. Apple also announced that Tor Myhren will join Apple in the first calendar quarter of 2016 as vice president of Marketing Communications, reporting to CEO Tim Cook.

“We are fortunate to have incredible depth and breadth of talent across Apple’s executive team. As we come to the end of the year, we’re recognizing the contributions already being made by two key executives,” said Tim Cook, Apple’s CEO. “Jeff is hands-down the best operations executive I’ve ever worked with, and Johny’s team delivers world-class silicon designs which enable new innovations in our products year after year.”

He adds: “In addition, Phil is taking on new responsibilities for advancing our ecosystem, led by the App Store, which has grown from a single, groundbreaking iOS store into four powerful platforms and an increasingly important part of our business. And I’m incredibly happy to welcome Tor Myhren, who will bring his creative talents to our advertising and marcom functions.”

Williams joined Apple in 1998 as head of worldwide procurement and in 2004 he was named vice president of Operations. Since 2010 he has overseen Apple’s entire supply chain, service and support, and the social responsibility initiatives which protect more than one million workers worldwide. Williams played a key role in Apple’s entry into the mobile phone market with the launch of the iPhone, and he continues to supervise development of Apple’s first wearable product, Apple Watch.

Srouji has spent nearly eight years at Apple as vice president of Hardware Technologies, overseeing breakthrough custom silicon and hardware technologies including batteries, application processors, storage controllers, sensors silicon, display silicon and other chipsets across Apple’s entire product line. Educated at Technion, Israel’s Institute of Technology, he joined Apple in 2008 to lead development of the A4, the first Apple-designed system on a chip.

With added responsibility for the App Store, Schiller will focus on strategies to extend the Apple ecosystem. He now leads nearly all developer-related functions at Apple, in addition to his other marketing responsibilities including Worldwide Product Marketing, international marketing, education and business marketing.

Tor Myhren joins Apple from Grey Group, where he has served as chief creative officer and president of Grey New York. Under his leadership, Grey was named Adweek’s Global Agency of the Year for both 2013 and 2015. As vice president of Marketing Communications at Apple, Myhren will be responsible for Apple’s advertising efforts and will lead a team that spans a broad range of creative disciplines from video, motion graphics and interactive web design to packaging and retail store displays.

Myhren will succeed Hiroki Asai, who earlier announced plans to retire after 18 years in graphic design and marketing communications roles at Apple.