Frequent news items demonstrate that the threat of attack against state information systems has become one of the vital elements to be taken into account in any national defence and security strategy. America’s 2010 Quadrennial Defense Review underlines the cardinal necessity of defending computer networks. Information technology operations are still today only a premonition: they need to inspire a strategic thinking process which will not limit their impact to just extending the capability for riposte, but the consideration of their place in a situation of strategic rupture.