An overview of the European project STRUCTURES and its main challenges is given. Current and foreseen Intentional Electromagnetic Interference (IEMI) threats are classified according to their availability, their technical characteristics (such as bandwidth) and their portability. Critical infrastructures are identified and their most characteristic aspects are highlighted, from an electromagnetic point of view. These concepts are used to establish a set of reference threats to be investigated and possible techniques to handle simulations and measurements in this complex environment are explored, emphasizing the use of the topological approach. © 2012 IEEE.