In military parlance the EM spectrum is just another battlespace, akin to the water or air battlespaces. Dominance simply means maintaining your freedom to act

In military parlance the EM spectrum is just another battlespace, akin to the water or air battlespaces. Dominance simply means maintaining your freedom to act in that space while simultaneously denying the adversary's. An EM battle can be won and lost without a "shot" fired. Look at the reports of GPS interference around Russia/Ukraine. That is probably the civilian-visible edge of the ongoing EM war.