If we don't declare it, it is not war. And it has to be actual war, not metaphorical war. Nor imaginary war ("fifth generation"). You just can't find the right crimes. Good ones are espionage and sabotage, but they are not the only ones. If you use "treason" as the broadswipe crime to accuse your enemies of performing, you are no better than Robespierre and the Reign of Terror.