Why doesn't China build its own global internet structure?

What?

This is a rather simplistic explanation but China essentially runs it’s own internal network just as the US does. This internal network, along with the US, and every other country in the world connect together to form what we know as the internet.

Are you sugesting China sets up infistructure all over the world that only allows communication to “them” similar to a giant office LAN (technically it would be an internal WAN)?