Zersetzung (German; variously translated as decomposition, corrosion, undermining, biodegradation or dissolution) is a psychological warfare technique that was first used by Nazi Germany as part of the accusation Wehrkraftzersetzung against political opponents (which typically resulted in death penalties). Decades later, during the Honecker era, the Stasi, the East German secret police used the accusation Zersetzung to silence political opponents by repression.
The "measures of Zersetzung", defined in the framework of a directive on police procedures in 1976, were used in the context of so-called "operational procedures" (in German Operative Vorgänge or OV). They replaced the overt terror of the Ulbricht era.
The practice of repression in Zersetzung comprised extensive and secret methods of control and psychological manipulation, including personal relationships of the target, for which the Stasi relied on its network of informal collaborators, (in German inoffizielle Mitarbeiter or IM), the State's power over institutions, and on operational psychology. Using targeted psychological attacks the Stasi tried to deprive a dissident of any chance of a "hostile action".
The use of Zersetzung is well documented due to numerous Stasi files published after East Germany's Wende. Several thousands or up to 10,000 individuals are estimated to have become victims, 5,000 of whom sustained irreversible damage. Pensions for restitution have been created for the victims.
The Stasi, or Ministry for State Security (German: Ministerium für Staatssicherheit, MfS) by its full name, defined Zersetzung in its 1985 dictionary of political operatives as
"...a method of operation by the Ministry for State Security for an efficacious struggle against subversive activities, particularly in the treatment of operations. With Zersetzung one can influence hostile and negative individuals across different operational political activities, especially the hostile and negative aspects of their dispositions and beliefs, so these are abandoned and changed little by little, and, if applicable, the contradictions and differences between the hostile and negative forces would be laid open, exploited, and reinforced.