Right, in future conflicts between major countries the satellites will be first casualties. The US military is aware of this and still trains personnel on analog navigation techniques. Inertial navigation works well for some missions and research is underway on alternative technologies. Civil airliners can still navigate without GPS, although this may reduce safety and increase workload.
We're also going to need a prompt launch capability to replace attrition losses. There should be warehouses full of spare navigation, reconnaissance, and communications satellites ready to mount on a reusable booster and launch within hours. Concerns have been raised over a "Kessler syndrome" due to orbital debris but in lower orbits with significant atmospheric drag this won't be a serious problem.
This is the easiest trick technique for figuring out vaguely north/south direction.
Take an analog watch. Say it is 9am, point the 12pm/midday point of the watch at the horizon directly below the sun, the half way distance between the hour hand and 12pm is the fairly close direction of the pole. So in that case, the 10:30am point would be the pole.
In the northern hemisphere it points South, in Southern hemisphere it points North.
This reminds me of this scene from Rosencrantz and Guildenstern Are Dead when they're trying to figure out whether Hamlet knows a hawk from a handsaw by the direction of the wind.
IIRC, the Navy stopped teaching officers traditional ship navigation methods for awhile, until the series of incredibly stupid incidents drew attention to the lack of basic navigation and piloting skills, then curriculums were partly reverted. Not sure if things have improved much; probably too early to tell.
I doubt officers or crew would ever have to resort to a sextant, but that's besides the point. It's the type of thing that's integral to learning navigation theory and building tacit knowledge that's fundamental to the job.
George Friedman suggests that the reason Washington is going back to the moon is that it is easier to launch satellites into Earth orbit from the moon than from the Earth's surface.
https://interestingengineering.com/military/us-military-nail...
We're also going to need a prompt launch capability to replace attrition losses. There should be warehouses full of spare navigation, reconnaissance, and communications satellites ready to mount on a reusable booster and launch within hours. Concerns have been raised over a "Kessler syndrome" due to orbital debris but in lower orbits with significant atmospheric drag this won't be a serious problem.