Earlier today, it was announced that the Chinese government was responsible for a massive breach of the Office of Personnel Management, hacking the files of four million current and former federal employees.
See: http://en.wikipedia.org/wiki/PLA_Unit_61398
Earlier this year, sources claim that the Russians were purportedly behind a hack of the Internal Revenue Service, also affecting several thousand US individuals. http://www.cnn.com/2015/06/04/politics/federal-agency-hacked-personnel-management/index.html
If memory serves us correctly, these types of overt acts are nothing short of sabotage and, in the past, led to the start of shooting wars. Witness the attack on the battleship Maine on February 15th, 1898, which led to the start of the Spanish-American War. Whether or not we are launching cyber-counterattacks to combat these regularly occurring incidents is anyone’s guess but it is becoming clear that there are governments that are willing to do anything to subvert our system.
See: http://en.wikipedia.org/wiki/Operation_Aurora
See: http://en.wikipedia.org/wiki/Operation_Shady_RAT