Also nontraditional warfare that has technically been seen but not really (at least in an officially acknowledged way, maybe something like stuxnet?) like offensive cyber warfare. If things truly came to trading blows russia does have very talented cyber espionage folks and the us has shown many times that it has pretty shocking vulnerabilities on many critical points of cyber infrastructure. these probably haven’t been attacked because it would be a literal act of war to go after the power grid, weapons systems, water delivery systems, etc but if the gloves come off then you better believe these systems start getting attacked by state sponsored actors who will never come anywhere near american land