There’s a quiet competition among the most aggressive nations of the world (US, Russia, China) where they hack each other constantly. It’s been in the news over and over the past couple years, this system compromised, that system compromised. The US is marginally more transparent than Russia or China, so we know about our failings whereas our attacks on them are generally kept quiet.
The US, in all it’s entrepreneurial spirit, has a homegrown private “Cyber-security” industry. In quotes, because in all reality, security and offense are the same thing. Attack your own systems to find weakness. Remove weakness. But, this “security” is really just internal attacks. What doesn’t kill you makes you stronger, with the added bonus that you can still use it to kill them.
Some day, it will escalate. Where and when, who knows? But it will and then we’ll see what computer warfare is all about.