HISTORY AND OVERVIEW OF JAPANESE INTELLIGENCE
DURING WW2

The history of spying in Japan dates back to Ninja spies, who were members of the elite Samurai warrior class. The Ninja Samurais mastered the art of making themselves invisible, the classic role of a secret agent.

Secret Japanese Societies played an important role in Japan's intelligence networks. Back in 1894, the Japanese Army Intelligence was supplemented by the Black Ocean Society during the war against China. The Black Ocean Society was a ultra nationalist group. The purpose of the Black Ocean Society was to expand Japan's influence overseas and collect Intelligence from China, Korea, Manchuria and Russia. 

In 1901 the Black Dragon Society split away from the Black Ocean Society. It's role was dedicated to the occupation of Manchuria which had been taken off China by Russia in 1898 through a 25 year lease. The Japanese Navy started intelligence operations in Russia and Manchuria.

After WW1, Japan sided with the Allies and Japanese Intelligence then monitored the German Colonies in the Pacific. Japan occupied Palau Island, the Marshall Islands, and the Caroline Islands after WW1. They used the islands as sea and air bases for their intelligence operations, spying on shipping lanes. Dutch New Guinea was a hotbed of Japanese espionage.

The Japanese Army Intelligence and Japanese Navy Intelligence Units were independent and did not share intelligence information, even at Imperial Headquarters.

The Japanese used their fishing fleets extensively before WW2 started to carry out intelligence gathering in and around Australia as well as to store caches of food, equipment, fuel and ordnance at strategic locations along the Australian coastline.

A number of Japanese Diplomatic, Naval and Military codes were being broken by the early 1930's. The Japanese became aware that their codes were vulnerable and they attempted to improve their enciphering systems. They abandoned their ordinary codes for military and diplomatic messages and changed to an Enigma machine-encoding system which they thought was more secure.

The Enigma system had been used by the Germans in the 1920s. In 1931 the Japanese Navy introduced a cypering machine known as Type 91. It was later known as "The Red Machine". A few years later a more complex encoder was introduced which was known as "The J Machine" which the Americans labelled as the "Purple Machine". By 1939, the American had also started to break Japan's Diplomatic code which was known as "Purple". They had fully mastered it by 1941.

The Japanese Naval Code, known as JN25 was being monitored by the British and Americans for a number of years before the War in the SWPA area started. By 1939, the British had the capability to read parts of the JN25 Naval Code. The Americans were also able to read parts of JN25 by 1941.

The U.S. Codebreaking effort was led from the Munitions Building in Washington by Colonel William F. Friedman. He had earlier broken another Japanese Code know as "Red".

The Japanese established a number of Espionage units, known as Kikan's. They assumed the name of their commanding officer. e.g Tokumu Kikan.

In January 1944, the Matsu Kikan (Pine Tree Secret Agency) commanded by Captain Masayoshi Yamamoto landed a reconnaissance Patrol in Western Australia near Cartier and Browse Islands. (Can anyone tell me more about this incident). They apparently stayed for 4 days on Australian soil. There were also a number of other Japanese landings on Australian soil during WW2.

The Japanese Bureau of Economic Research carried out widespread propaganda campaigns in the Netherlands East Indies. The Bureau was a training school for Spies.

Japanese and other Axis Powers Intelligence Units
and other Secret Units during WW2

Can anyone help me with more information?

"Australia @ War" WWII Research Products

This page first produced 14 April 2002

This page last updated 17 January 2020