After the start of the war, Himmler and Heydrich began to deploy and extend their terror apparatus in "defense of the home front." Above all, the Security Service [Sicherheitsdienst or SD], the SS, and the Gestapo were responsible for spying on the general German population under the pretense of a war-induced state of emergency. Threats to internal security or to the troops' military readiness were avenged and punished with ever greater severity. Such threats not only included transmitting information important to the war effort, but also, for example, listening to foreign radio broadcasts or spreading negative information about the course of the war.
This poster aimed to dissuade women from discussing information included in personal letters from loved ones at the front. One female office worker says to another: "Hans writes that his division is coming back . . . " The message warns, "Pst! The enemy is listening in!"