It's hard to deter, because attribution is a big problem in the cybersecurity world. You can do attacks with little or no risk of being detected. Even if it is detected, you can always claim that there has been some configuration error or mishap, etc. It's very hard to show that there's really malicious motivation behind what is happening. You can see a hijack attack, which can also be a configuration error. To distinguish this, you really need to put somebody in a room and force him to tell you what the truth is.
In Israel we have a national defence program through which we monitor the routes towards critical infrastructure in Israel.