The former Soviet Union had heavily invested in Radio Electronic Combat, and there is no reason to assume the successor Russian government has not continued along these lines.
The first and simplest way to use Radio Electronic Combat is signals spoofing and jamming. We normally associate radio jamming with powerful "Barrage" jammers flooding the airwaves with white noise, but jammers can be very specific and jam single frequencies or a spread. The Soviets also introduced "silent" jamming, where the air is deceptively quiet, but upon using the radio you have no transmission or reception (this works best when initiated in a quiet zone during a period of low radio traffic, the net is naturally quiet then and you may not notice the initiation of silent jamming). Spoofing is just what it sounds like; skilled linguists are monitoring the net and at the appropriate time they begin transmitting as well. Unless the rest of the operators can catch on quickly, they may end up talking to the unknown operator assuming it is a replacement, or worse yet, taking orders and information from them.
Modern communications systems use encryption and techniques like frequency hopping to limit the ability to jam, spoof or listen in to a net, but since the net continues to emit energy every time a radio is used, Direction Finding allows you to discover the locations of the radios (or their radio antenna, at least), allowing you to direct physical attacks against the transmitters. Jamming can still work as well, even interrupting a percentage of the message could degrade the information enough to slow down operations as requests for clarification and having the message repeated become a larger percentage of the traffic on the net.
Cyber-warfare falls into this as well, and various forms of malware exist, ranging from crude to very sophisticated. Once again, the more sophisticated attacks are "better" since the opponent might not realize that their data and communications have been compromised. Examples like the Stuxnet worm released against the Iranians or the Chinese theft of personal data of millions of American government employees show large scale attacks can be running for years before discovery, and the effects can be very subtle (causing the centrifuges to run at sub optimal speeds in the Iranian nuclear enrichment program, or allowing the Chinese to apply pressure against individual Americans to support espionage, economic or military goals).
Finally, using enough energy can simply overwhelm the defenders electronic systems, rendering them inoperative. The best known example is EMP, which can be triggered by nuclear and non nuclear means and introduce enough energy in circuitry to physically damage or destroy them. This can be scales from frying individual units, computers or antenna to pumping enough energy into the electrical grid to cause the entire nation to be blacked out.