The reason behind this labeling of the iPhone as a national security threat? It has been attributed to the iOS’ ability to track down a user’s location, where a China Central Television (CCTV) report claims that this could be used as a modus operandi to betray Chinese state secrets to the whole world.
Apparently, the iOS’s “Frequent Locations” feature that keeps track of the geographic coordinates of places where a particular user frequents the most, could be used to leak sensitive information and state secrets to Apple, which is a totally baseless assumption according to Apple since all data gathered by this particular feature will remain on the iPhone itself, and will require the user’s consent prior to sending such data to Apple. After all, one can also turn off Frequent Locations if it is so much of a bother.