An attack is an attack regardless of the prefix "cyber", says the United States

So here’s an interesting development in international diplomacy and online security. A newly issued report by the Obama administration, entitled International Strategy for Cyberspace, suggests a much more global approach for NATO countries to employ in order to fight hackers. Obviously if an army of tanks and planes invades a NATO country, all the other NATO countries take that as an invasion of themselves and act accordingly. The U.S. wants cyber invasion to be seen the same way. “The world must collectively recognize the challenges posed by malevolent actors’ entry into cyberspace, and update and strengthen our national and international policies accordingly. Activities undertaken in cyberspace have consequences for our lives in physical space, and we must work towards building the rule of law, to prevent the risks of logging on from outweighing its benefits.”

The Pentagon reports that it gets millions of probes from hackers every day.