Central Bureau, Southwest Pacific Area

A joint U.S.-Australian unit, the Central Bureau of the Southwest Pacific Area (SWPA)' was a intelligence organization, primarily but not exclusively dealing with communications intelligence, whichsupported Douglas MacArthur. It focused on Japanese ground and air communications, complementing the naval Fleet Radio Unit Melbourne (FRUMEL).

Central Bureau was commanded by Major General S. B. Akin, who had been MacArthur's Chief Signal Officer, and formerly with the Army's Signals Intelligence Service. It did not appear to be under the direct control of MacArthur's intelligence officer, Charles Willoughby. MacArthur had had problems, prior to moving to Australia, with intelligence cooperation with the Navy, but Willoughby's difficult personality may have contributed to the problem. That the Allied Intelligence Bureau did report to Willoughby suggests this arrangement was no accident.

Other Allied intelligence units included:
 * Allied Geographic Service provided topographic information on this little-mapped theate which produced maps and geographical data about the SWPA
 * Allied Translator and Interpreter Service (ATIS) which interpreted millions of captured documents, intercepted messages and interrogated thousands of Japanese POW's
 * Allied Intelligence Bureau for human intelligence; MacArthur had banned the Office of Strategic Services
 * 1st Reconnaissance Battalion (Special), and its attached 978th Signal Service Company inserted radio-equipped teams by submarine into the islands to link with the guerrillas and collect intelligence. secret "Camp X", near Beaudesert south of Brisbane in southern Queensland. . This unit was a key part of operations behind Japanese lines, including communicating with guerrillas and the Coastwatcher organization under Central Bureau. It also sent radio operators to the guerrillas, and then moved with the forces invading the Philippines.
 * the Australian Coast Watching Service
 * a POW interrogation center.
 * Section 22, General Headquarters, SWPA, also under Akin but including Navy and Marine Corps, with an electronic intelligence mission against Japanese radar

Central Bureau
After consultations between Australian and US signal and communications senior staff, MacArthur ordered Central Bureau to be created, partially to avoid his being dependent on Navy SIGINT. Central Bureau was made up of:
 * The intelligence section of the former No. 4 Australian Special Wireless Section
 * Australian Military personnel
 * RAAF personnel
 * US Army intelligence personnel who had escaped from the Philippines
 * US Army intelligence personnel from USA (6 officers and 8 men of the 837 Signals Service Detachment)
 * British intelligence staff from Singapore

At first, Central Bureau was made up of 50% American, 25% Australian Army and 25% Royal Australian Air Force (RAAF) personnel, but additional Australian staff joined. In addition, RAAF operators, trained in Townville in intercepting Japanese telegraphic katakana were integrated into the new Central Bureau.

Cryptanalysis
Assistant director for this function was Abraham Sinkov, one of the first cryptanalysts trained by William Friedman.

Central Bureau broke into two significant Japanese Army cryptosystems in mid-1943. The US Army had shared, with the Navy, the Purple attack on Japanese diplomatic cryptosystems. Many histories assume Purple included Japanese military cryptanalysis, but those were separate projects, although generally under the same organizations.

Non-cryptanalytic COMINT
After creation of the Army Signal Security Agency, the cryptographic school at Vint Hill Farms, Warrenton, VA, trained analysts. As a real-world training exercise, the new analysts first solved the message center identifier system for the Japanese Army. Until Japanese Army cryptosystems were broken later in 1943, the order of battle and movement information on the Japanese came purely from direction finding and traffic analysis.

Traffic analysts began tracking Japanese units in near real time. A critical result was the identification of the movement, by sea, of two Japanese infantry divisions from Shanghai to New Guinea. Their convoy was intercepted by US submarines, causing almost complete destruction of these units.