Following the 1975 West German Embassy siege in Stockholm, the German Red Army Faction (RAF) terrorist Norbert Kröcher allegedly planned to kidnap Anna-Greta Leijon. The goal was to exchange Leijon for 8 of his comrades held in German prisons. The plan, known as Operation Leo, was intercepted by the Swedish Security Service (Säpo) and Kröcher and other team members was arrested on 31 March in Stockholm.