Maybe GJC2 can be modified on the fly, by changing offset parameters? So in a hypothetical war situation, only providers obtaining data in realtime from "authorized" sources would have access to accurate targeting information.
Nah, because the thing is the Russian and US militaries will have their own maps of China anyway. There's a reason the UK's mapping agency retains the historic name of the Ordinance Survey, maps has always been a military thing and they've always retained surveyors.
This reminds me of a fascinating book titled "The Red Atlas" by John Davies and Alexander Kent which is about the very detailed maps of Western cities the Soviet Union created during the Cold War.