fate.met
When nothing else works, radio works. Get a good shortwave receiver that covers the whole HF band. Better yet, get a general or extra class ham license and get on the air on the HF bands.
VHF and UHF are useful for local comms, but are line of sight. On HF, even 100 watts is transcontinental. Learn what NVIS is and when it might be extremely useful. Extremely useful.
If the military and NGOs use it, there's a reason. It works.