'Thrush Red' was a British operation by the Special Operations Executive for B. Fjelstad and N. Gabrielsen to enter German-occupied Norway overland from Stockholm in neutral Sweden (June 1943).

Fjelstad was to work as an instructor in the area to the east of Oslo whilst Gabrielsen established radio contact. The two men were also instructed to attempt to blow up the Prestebakke bridge in eastern Norway, but this task was soon abandoned. Fjelstad began training in his designated area, and then aided the local resistance by working as an instructor for the 'X-Groups'. Gabrielsen moved to Oslo to assist the central leadership of the Norwegian armed resistance movement by training radio operators and helping establish four new radio stations. He remained connected to the central leadership and helped it to establish an internal communications network.