Apple's Cook & Facebook's Zuckerberg meet with Chinese President Xi

Both Cook and Zuckerberg are on the advisory board of the Tsinghua School of Economics and Management, Reuters noted. An Apple spokeswoman declined to comment on Cook's "schedule and/or meetings," but Zuckerberg publicly acknowledged his trip to Beijing in a Facebook post. It's unknown what the trio discussed.

Both CEOs have a strong incentive to ingratiate themselves to Xi, who recently consolidated more power at this year's Communist Party Congress. Facebook has been blocked in China since 2009, and Apple is not only on the verge of launching the iPhone X in the country but dealing with censorship at the App Store, disabled LTE on the Apple Watch, and Qualcomm lawsuits threatening to stop iPhone production.

Apple also recently established its first data center in the country in order to comply with local laws, and risks having that center raided or shut down if it offends the Communist leadership.

Earlier today, Canalys research suggested that the iPhone 8 has been doing reasonably well in China, reversing a long-standing decline in local iPhone sales.