 On 17 November 1939 , Naval High Command ( SKL ) issued orders for U @-@ 36 and U @-@ 38 to scout the location for Basis Nord , a secret German naval base for raids on Allied shipping located off the Kola Peninsula and provided by the Soviet Union . The mission required coded messages to be flashed to Soviet naval vessels patrolling the area preceding a Soviet escort to the prospective base location . 
