A foreign government hacks and takes down the network of a bank, or a hospital, or a government contractor. Does the private company respond? Does the government? Can the response be physical? Should the rules change if the hack is conducted by a non-governmental entity? As everything we do becomes reliant on data and communications, everything we do becomes hackable. What role can and should the government play in preventing, responding to and mitigating cyber attacks, and what level of cyber attack constitutes and act or war?