Of course state-sponsored cyber-terrorism is possible and by all accounts, has already occurred with the release of Stuxnet targeting the Iranian centrifuges. While it's all well and good to make preparations and even to pretend that you're prepared, the reality is that the creative mind will always find the means to disrupt and there's very little that can be done about it. Maintaining a moderate political stance may reduce the likelihood, but that's about as popular as suggesting that weight-loss can be achieved by exercise and good eating rather than a magic pill...