In a speech delivered on 28 November 1932, at the Madrid Ateneo, the poet Miguel de Unamuno, one of the founding fathers of the Second Spanish Republic, angrily denounced the Red Terror by the Republican forces: "Even the Inquisition was limited by certain legal guarantees.

But now we have something worse: a police force which is grounded only on a general sense of panic and on the invention of non-existent dangers to cover up this over-stepping of the law.

"[1] In 1937 there were nine intelligence and counter-intelligence organizations with their own networks of agents in the Republican held zone: the communist held DEDIDE (Departamento Especial de Información del Estado), the SIEP (Servicio Especial de Información Periferico), the army’s secret service, the Carabineros’ secret service, the foreign ministry’s, the Generalitat’s, etc.

[2] Owing to the confusion and often arbitrary arrests, the Republican minister of Defense, Indalecio Prieto decided to reorganize the intelligence services in order to increase the control of the central government.

The main goals of the SIM were to combat the Nationalists' intelligence service, the SIPM (Servicio de Información y Policía Militar), to neutralize the Fifth Column and to restrict the activity of the "uncontrollables".