https://www.cnbc.com/2018/02/24/apple-moves-to-store-icloud-keys-in-china-raising-human-rights-fears.html

When Apple begins hosting Chinese users' iCloud accounts in a new Chinese data center at the end of this month to comply with new laws there, Chinese authorities will have far easier access to text messages, email and other data stored in the cloud.

That's because of a change to how the company handles the cryptographic keys needed to unlock an iCloud account. Until now, such keys have always been stored in the United States, meaning that any government or law enforcement authority seeking access to a Chinese iCloud account needed to go through the U.S. legal system.