I’m not trying to defend china, but I just want to point out, that to my understanding, U.S. has the same kind of practice. Government can order that companies must create back doors in their software and at the same time order, that it is forbidden to tell anyone about those back doors.Well since the ground equipment will likely be made in China the easiest way to do it would be for them to install something while they are making it. Could be a lockout based on GPS or just a setup that will forward the traffic to China servers so they can monitor it. It wouldn't be the first time a government had things added to equipment.
I’m pretty sure, NSA can access all the information, which goes trough U.S. companies.