The SYSTEM project will design and demonstrate a data fusion system for the continuous monitoring of threats associated to the manufacturing of explosives and to the production and handling of synthetic drugs. Data fused from different mature sensor networks will provide Law Enforcement Agencies with enriched information to assess the potential occurrence of a criminal activity (e.g. to localize the production of improvised explosive devices and/or clandestine synthetic drugs laboratories) in an identified area. Forerunners and basis of SYSTEM are two H2020 IA projects, NOSY and microMole, funded under the call FCT-05-2014. SYSTEM devices will support the detection of home-made explosives and synthetic drugs manufacturing by detecting intermediates and impurities of the production process and precursors used for their synthesis, identifying abnormal use of chemicals transported/provided within the covered urban areas. Additionally, the prevalence of new psychoactive substances including metabolites in the sewage system will be assessed. Deploying a network of sensing systems, working in different and complementary utilities and environments, SYSTEM will acquire and process data from the sewage wastewater and solid waste networks as well as air emissions from target areas in real-time. Such network will consist of different sensing systems, working in different and complementary utilities and environments, Metal-Oxides (MOXs) sensors, Molecular Imprinted Polymers (MIPs), Liquid Chromatography with Mass Spectrometry and autonomous sampling (online LC/MS), fast Gas-Chromatography with Photoionization Detection (GC-PID) and commercial pH and conductivity sensors combined with passive sampling devices and integrated into SYSTEM through a centralised monitoring centre. The consortium will test and demonstrate functionality of SYSTEM in seven different European cities during three years of activities