Japanese Intelligence Operations in Scandinavia during World War II

Abstract

Japanese intelligence operations in Scandinavia became active after the collapse of Poland in September 1939. Both the Japanese and the Finns exchanged information on Soviet military cryptography and tried to decrypt the enemy's codes. As a result of the cooperation, the Finns succeeded in decrypting Soviet naval code at the beginning of the Continuation War. Onodera Makoto, Japanese military attaché in Sweden, collected a lot of valuable information on the Allied Powers in the neutral country, though the General Staff in Tokyo disregarded them as unreliable.