According to Business Insider, "[Apple] worries that some of the equipment and cloud services it buys has been compromised by vendors who have agreed to put "back door" technology for government spying, according to a report from The Information's Amir Efrati and Steve Nellis."
With many of its cloud-based services like iTunes, the App Store, and iCloud requiring enormous data center to operate, Apple hasn't been able to build all the data centers it needs, and has instead been using services from its rivals, namely Amazon Web Services and Microsoft.
Google recently landed Apple as a customer for the Google Cloud Platform.
"Meanwhile, [Apple] has embarked on yet another attempt to build more of its own data centers to handle all of that, called Project McQueen, reports Jordan Novet at VentureBeat, and the project is having a rough go of it, reports The Information."
Apple suspects that backdoors have been added to many of the servers it has been ordering from others.
"At one point, the company even had people taking photographs of the motherboards in the computer servers it was using, then mark down exactly what each chip was, to make sure everything was fully understood."