For those who understand GPS signals can be jammed, and used in a cyber-war situation, have a look at this evidence:
For those who not aware, learn and prepare.
This has happened a couple times in the U.S. Most recently in Dallas this year.
GPS Signal Mysteriously Disrupted Around Dallas Airports - Phil Stock World
Fortunately, the effects seem to be incredibly localized.
However, jamming GPS signals is hard and very, very illegal. Do that at any radius greater than your property and you can be subject to all sorts of hurt.
Caregiver Connect Aurora
HI @Judyblanks if another nation wants to take down a GPS system, it is relatively easy.
Given the experience some of us have had, it is a likely target in any conflict.
Illegally does not come into it then, they just do it immediately - it is a strategy.