Protecting critical infrastructures has become a major security stake since September 11th, 2001. Following in the United States’ footsteps, public powers globally have reassessed their Cold-War concepts and adapted them to the necessities of the times. Defense against terrorist threats has thus become the main objective of protection policies. This text shows how France has implemented its new protection strategy for « vital » infrastructures, and reveals the action of international organizations, especially the European Union, in this field. It also emphasizes a potentially enduring conceptual trend: that States define rules and obligations and that operators bear the financial burden, lest severe sanctions be inflicted upon them.