Northrop Grumman says it's successfully flight tested a jam-proof navigation system to replace the current gear on military aircraft. Embedded Global Positioning System (GPS) / Inertial Navigation System (INS) Modernization, known as EGI-M, was installed on a Cessna Citation and put through its paces in May. The core of the system is something called an M-Code capable GPS receiver that can "quickly transmit positioning, navigation and timing information" in "GPS-contested and GPS-denied environments."
This is great for basic stuff. The real issue is when we eventually come to blows with China, the first things to go will be our GPS satellites. Unless they can protect them, it’ll be back to VORs and DMEs… Ugh!
A coordinated GPS/INS isn’t a new thing at all. (Nor is infrared vision in the cockpit to see through fog.)
There simply hasn’t really been a perceived need for it in the past.
We will not, in our lifetimes, “come to blows with China”. Our economies are intertwined to such a degree it would be disastrous for both. But expect the bluster to continue.