'Antrum Green' was a British operation by the Special Operations Executive in succession to 'Antrum' in German-occupied Norway (January/September 1944).

Delivered by sea, Knut Aarsæther took over from his brother K. J. Aarsæther in tasks such as continuing radio contact with the UK, providing intelligence, arranging sabotage of shipping and communications, forming a group to carry out sabotage, and preparing to police the area in the event of a German withdrawal. Knut Aarsæther remained in the area until September and organised resistance groups and their weapons instruction, laid plans for demolishing ferries, and began a whispering campaign aimed at mobilising the Norwegian fishing fleet should an Allied invasion be made.