I remember when hacking into the Democratic Party and publishing the juicy details would just have been called "journalism", albeit a fairly low level of journalism.
Before my time, Richard Nixon just called "politics".
But now, apparently, it is called "cyberwarfare".
Nevertheless, assume that the future battlefields are indeed in cyberspace.
If, for the sake of argument, Vladimir Putin could cut off the power supply to London at the touch of a button (resulting, yes, in some deaths, such as in hospitals or on the Tube), then why would he need a nuclear bomb?
And if, for the sake of argument, Theresa May could cut off the power supply to Moscow at the touch of a button, then why would she need a nuclear bomb, either?