As a former Marine (07-12), yes, they do still teach basic land navigation using a map and compass.

However, the skills are not reinforced or even practiced really. It is not as easy to conduct EW against GPS as you would think, at least not military specific capabilities. There are contingencies and capabilities in place for that.

Bigger concern would be the GPS satellites being destroyed altogether.

Which is also why when you hear news reports about China or the US destroying their own satellites using ship launched missiles, the message intended to be conveyed is more than meets the eye.

Those demonstrations are really about telegraphing to adversaries what you can/would do in the event of a conflict.

Would that really matter, given the existence of

[1] https://www.microsemi.com/product-directory/clocks-frequency... ,

[2] https://en.wikipedia.org/wiki/Ring_laser_gyroscope ,

[3] https://en.wikipedia.org/wiki/Fibre-optic_gyroscope ,

and other

[3] https://en.wikipedia.org/wiki/Microelectromechanical_systems

gizmos like

[4] https://en.wikipedia.org/wiki/Vibrating_structure_gyroscope#... ?

Especially when global

[5] https://en.wikipedia.org/wiki/Digital_elevation_model

fit multiple times on the equivalent of some micro-sd card nowadays?

Seems like something like this

[6] https://en.wikipedia.org/wiki/Synthetic_vision_system

wouldn't need to depend on GPS at all, maybe some sensor fusion for things like radar/infrared/whatever.

I’m not very familiar with the technologies you linked. However, bear in mind the military operates at a scale that’s hard to fathom. Fielding new capabilities requires substantial level of effort when it’s military wide. Aside from that, many times they already have some tricks up their sleeves if push ever came to shove.

Me neither, except on a pop-science level.

Anyways, what I linked to are the key components for inertial navigation systems. Not all of them together, but several options. The first is that chip-scale 'atomic clock' thing from microsemi, a very precise time source. Something like that would be needed in every case.

The others are different possible paths to precisely measure (speed of) movement and (change of) orientation. Based on those you could construct inertial navigation 'on the go' in small form factors. Not smartphone-like small at the moment, but close to.

Regarding the scale of fielding/roll-out, ask Apple, Honeywell, or someone like that...

Thinking about it, maybe that is why 'the others' play at shooting things in orbit because they allready have 'Mao's mighty map' available? Who knows? Whatever. The end of GPS/GNSS wouldn't necessarily have to be 'the end of navigation'.

A couple of things make that not so easy:

1. Ship- and ground-based transmitters are ridiculously powerful, and use lots of jamming-resistant tech like spread spectrum.

2. Viewed at the right wavelengths, jammers are like looking at Las Vegas at night. They’re very visible, and attractive targets for RF-seeking munitions.

> 2. Viewed at the right wavelengths, jammers are like looking at Las Vegas at night. They’re very visible, and attractive targets for RF-seeking munitions.

This may not be super intuitive until you start playing around with the technology and understand what’s possible with phased array antennas. I’m fairly confident that somewhere in the planet is an integrated, real-time, broadband view of RF illumination over the surface of the earth.

Yeah, your missiles don't need fancy GPS guidance when their programming can basically just be "travel towards the radio jamming signal and explode on impact"