An EMP large enough to be an international incident is a nuclear explosion. The effective range of one pumped by a conventional explosive is very small.
For undirected EMPs, consider that a lightning strike is in the region of about 5 gigajoules, and the difficulty of pumping that much energy through a coil.
My expectation is that a CHAMP warhead (not missile, warhead) would have a EMP range of something under 300m (probably less), even then vs. unshielded electronics (compare the effect on your body of being in a car that's struck by lightning vs. being on a 100m away on an open field that's struck by lightning), and only even that much by having a high gain (highly directional) antenna: https://en.wikipedia.org/wiki/Counter-electronics_High_Power...
That said:
> but with the low wattages many non-military communication devices use today you would also be blasting horrible noise to all of them beyond the local area and disrupting communications across potentially multiple neutral countries.
For undirected EMPs, consider that a lightning strike is in the region of about 5 gigajoules, and the difficulty of pumping that much energy through a coil.
My expectation is that a CHAMP warhead (not missile, warhead) would have a EMP range of something under 300m (probably less), even then vs. unshielded electronics (compare the effect on your body of being in a car that's struck by lightning vs. being on a 100m away on an open field that's struck by lightning), and only even that much by having a high gain (highly directional) antenna: https://en.wikipedia.org/wiki/Counter-electronics_High_Power...
That said:
> but with the low wattages many non-military communication devices use today you would also be blasting horrible noise to all of them beyond the local area and disrupting communications across potentially multiple neutral countries.
This doesn't need an EMP, it's "just" jamming, and Russia (amongst others) already does this: https://gpsjam.org/?lat=50.32113&lon=41.41602&z=3.0&date=202...