John Ternus officially became Apple's chief executive Tuesday, concluding Tim Cook's 15-year leadership that saw the company's valuation surge to $4.6 trillion, largely driven by the success of the iPhone.

The leadership transition occurs at a critical juncture for Apple, as artificial intelligence presents a significant industry shift comparable to the introduction of the iPhone in 2007. The company has faced early hurdles in developing and delivering AI-powered features, a field where rivals have made substantial progress.

Earlier this year, Apple announced advancements in artificial intelligence, including updates to its Siri assistant, with an emphasis on user privacy and practical applications. These efforts aim to help Apple regain ground in the competitive AI landscape.

Ternus, whose background is in hardware engineering, will need to expand his focus beyond product development. Key challenges include maintaining Apple's competitiveness in the AI race, navigating complex global supply chains, and managing relationships with international figures, including former President Donald Trump, who publicly acknowledged Cook's contributions.

Cook cultivated relationships with political leaders, including Trump, to manage business complexities such as trade disputes and tariffs affecting Asian manufacturing operations. Cook is expected to continue influencing the company's relationship with key figures in his new role as executive chairman.

During his tenure under Cook, Ternus contributed to the development of significant Apple products such as the Apple Watch, AirPods, and Apple Vision Pro. He is set to lead the unveiling of the newest iPhone model next week at Apple's headquarters in Cupertino, California.