Zersetzung (pronounced [t͡sɛɐ̯ˈzɛt͡sʊŋ], German for "decomposition") is a psychological warfare technique used by the Ministry for State Security (Stasi) to repress political opponents in East Germany during the 1970s and 1980s. Zersetzung served to combat alleged and actual dissidents through covert means, using secret methods of abusive control and psychological manipulation to prevent anti-government activities.

Directive No. 1/76 on the Development and Revision of Operational Procedures, which outlined the use of Zersetzung in the Ministry for State Security.

Erich Honecker's succession to Walter Ulbricht as First Secretary of the Socialist Unity Party of Germany (SED) in May 1971 saw an evolution of "operational procedures" (Operative Vorgänge) conducted by Stasi away from the overt terror of the Ulbricht era towards what came to be known as Zersetzung ("Anwendung von Maßnahmen der Zersetzung"), which was formalized by Directive No. 1/76 on the Development and Revision of Operational Procedures in January 1976.[1] The Stasi used operational psychology and its extensive network of between 170,000[2] and over 500,000[3][4] informal collaborators (inoffizielle Mitarbeiter) to launch personalized psychological attacks against targets to damage their mental health and lower chances of a "hostile action" against the state.[5] Among the collaborators were youths as young as 14 years of age.[6]

The use of Zersetzung is well documented due to Stasi files published after the Berlin wall fell, with several thousands or up to 10,000 individuals estimated to have become victims,[7]:217 and 5,000 of whom sustained irreversible damage.[8] Special pensions for restitution have been created for Zersetzung victims.