By Justin Pyke
Editorial Note: In the second part of a three-part article, Justin Pyke examines American intelligence assessments of Japanese air power during the inter-war years. This second part examines issues between 1930 and 1937. Part one of this article can be found here.
The early and mid-1930s brought with them a fundamental change in the trajectory of the Japanese air services. Their dependence on foreign technology and assistance began to decrease at the same time American intelligence assessments began to drop noticeably in overall quality. This decline stemmed partly from the dramatic improvement of Japanese information security and the increasing influence of preconceived notions of Japanese unoriginality. Observations concerning the Japanese aviation industry and the broad strategic value of air power remained consistent and accurate, while opinions of Japanese personnel became increasingly contradictory.
Western observers were forced to rely increasingly on open sources in place of the informative avenues that they had used previously. The Japanese press reported generally on the air services, and the frequency of reports that paraphrased such news stories gradually increased and replaced the detailed assessments derived from other sources. The amount of information gathered through tours of air stations declined dramatically from 1930-37. Additionally, Western aviation experts and military officers were treated increasingly like spies. The Americans still were able to gather much intelligence regarding strategic and industrial issues, but nothing provided the kind of detailed tactical and technical information that they had grown accustomed to having during the 1920s.
The assessments that came out of Japan from 1930 to mid-1937 continued to accurately track the rapid expansion of the air services, along with the problems that constantly plagued the aviation industry. A June 1930 report contained comprehensive details concerning aircraft production across the dozens of factories that had sprung up in the country. For example, the Kawasaki Dockyard Company in Kobe possessed approximately 200 machine tools in its aircraft and engine factory, almost all of American manufacture. The Japanese had relied heavily on the importation of foreign machine tools during the 1920s and did so even more as the industry expanded. Despite the continuing weakness of the Japanese aviation industry, the author of another report was surprised at the ‘remarkable strides’ that the Japanese Army (IJA) and Navy (IJN) had taken during the previous year, both in quality and quantity of production. Strategy drove these strides. The IJN wished to use air power to overcome the disadvantage in the surface fleet institutionalised by the Washington and London naval arms limitation treaties, and the Imperial Japanese Army Air Service would undergo a similar expansion following the annexation of Manchuria and the 1932 Shanghai Incident.
Foreign observers closely followed Japan’s increased efforts to expand the air services. In 1934, the Soviet State Military Publishing Bureau published a book on the Japanese air services written by D. Streshnevsky. His views on the quality of Japanese industry roughly coincided with those of the Americans. The book listed all the aviation-related factories in Japan and noted that almost every single one had been enlarged, reconstructed, or both. Despite these strides, the aviation industry still depended on imports. Fuel was the most critical shortage, due to Japan’s complete lack of indigenous sources. Such discussions of strategic resources and industrial capability were a staple of intelligence assessments of Japanese aviation, justifiably. In 1936, the American military attaché provided an excellent summary of the strategic and industrial elements of Japanese air power. He noted aircraft manufacturing, which already struggled with a lack of skilled workers, would be hindered even more after the outbreak of hostilities due to the need for expanded production while making use of the same limited pool of the workforce. Additionally, factories could easily be deprived of the raw materials needed to manufacture aircraft of quality and quantity. Another report noted the slow rate of aircraft production meant that Japan was unable to maintain a sufficient aircraft reserve:
planes designated as ‘reserve planes’ are used as much as those in service, and the number may vary from none at all to a disproportionate percentage, especially where units are being equipped with new models.
Overall, reports stressed that Japanese industrial practices were rapidly improving, but still struggled with many inherent weaknesses, such as a reliance on foreign techniques and a shortage of skilled labour, raw resources, and machine tools.
Appraisals of Japanese technological progress began to slip in quality during the early and mid-1930s. The preconception that the Japanese were incapable of extensive technical innovation in aviation, which had been true during the 1920s, began to mask the Japanese progress in the area from the early 1930s. It is telling that the translation of Streshnevsky’s work was the only report from the American naval attaché’s office that emphasised Japan’s growing inventive capabilities. Mr Parker of the Bristol Company expressed the typical Western view when he described the Japanese as ‘notorious copyists.’ Instead, by 1930 the Japanese were modifying foreign designs to fit their own needs rather than simply copying them wholesale, and an increasing number of designs were entirely of Japanese origin. Several capable indigenous aircraft were designed or entered service from 1933-37, such as the G3M Land-Based Attack Aircraft (‘Nell’), and combined to bring the Japanese air services up to rough technological parity with the West by the late 1930s. By the outbreak of the Second Sino-Japanese War in July 1937, the Japanese had achieved independence in the field of aviation design and manufacturing, something that went unnoticed by American observers.
American assessments of the quality of Japanese pilots, mechanics, and workers were increasingly varied and contradictory. Philip G. Lucas of the Hawker Company stated that the Japanese were ‘competent’ pilots who should not be underrated, implying that the common views held in the United States and Great Britain were inaccurate. Parker and Mr Burgoine of the Bristol Company both agreed that the Japanese were ‘excellent’ fliers, but exhibited a lack of initiative and originality in their flights. Two foreign air force pilots, one British and one German, were given increasingly rare opportunities to witness Japanese pilots in flight while they toured IJA and IJN air stations in early 1935. They both concluded the Japanese were ‘good’ pilots, but the Englishman noted that the Japanese were more ‘conservative’ in their manoeuvring. Streshnevsky’s analysis of Japanese air performance over Shanghai in 1932 left a poor impression. Japanese bombing was ineffectual because of poorly trained pilots and insufficient bomb loads. While reports on aircrew quality were contradictory, American observers continued to accurately note that Japan lacked the depth of aircrew reserves to keep up with the rate of attrition in a high-intensity air war.
Americans assessed Japanese mechanics and workers much as they did their flying compatriots. Mr R. Moffett of the Wright Aeronautical Corporation condemned all the Japanese engineers, mechanics, and workers with whom he worked. Engine mechanics, ‘lamentably poor’ when tasked with correcting minor difficulties with auxiliary equipment, had to be shown the exact detailed procedure to follow. Enlisted men appeared ‘stupid.’ Moffett concluded that the Japanese ‘are striving far beyond their capabilities in the engine field.’ Other Western aviation representatives had kinder words for Japanese personnel. Lucas described the Japanese mechanics whom he met as ‘extremely intelligent’ and rated the overall quality of Imperial Japanese Navy Air Service maintenance personnel as ‘very high.’ Burgoine and Parker believed that the Japanese could learn rapidly through experience, and thought the mechanics in the aviation industry well-trained and ‘excellent,’ but lacking experience with machine tools.
The American intelligence assessments of Japanese air power from 1930 to mid-1937 remained excellent regarding industrial and strategic issues but were noticeably less accurate regarding technology and tactics. Japanese military aviation had been an open door for intelligence gathering in the 1920s, but the opening gradually narrowed through the early 1930s and slammed shut with the start of the war in China in 1937. The preconception of Japanese unoriginality, particularly regarding aircraft design, became increasingly influential during the 1930s at a time when Japan was moving away from its foreign dependence. Meanwhile, the opinions concerning the quality of Japanese air and ground crews were diverse, varying wildly from praise to derision and everything in between. The lack of a clear and consistent snapshot of Japanese personnel became a major problem in the late 1930s, as did the assumption that the Japanese could not innovate in the aviation sphere.
Header Image: Nakajima Ki-27 at Nomonhan during the Battle of Khalkhin Gol, c. 1939. This indigenous IJAAS fighter entered service in 1937. (Source: Wikimedia)
 E-8-a 21984, Japanese Army desires for Unification of Army-Navy Air Service Opposed by Navy, March 20, 1936, Naval Attaché Reports, 1886-1939, Box 732, RG 38, NA.
 A-1-l 19973, Tateyama Naval Air Station, December 4 1930, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA; A-1-l 19973, Tateyama Naval Air Station, January 30 1932, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA; A-1-l 19973, Tateyama Naval Air Station, December 4 1933, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA; A-1-l 19973, Tateyama Naval Air Station, December 31 1935, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA; A-1-l 19973, Tateyama Naval Air Station, December 24 1936, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA.
 2085-810, Military Aviation – General: Attachment of British Officer to the 4th Air Regt., February 10 1937, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America, p. 2, 15; A-1-a 21684, British Estimate of Japanese Aviation, Continued, May 1 1935, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA, 1; A-1-a 21684, British Estimate of Japanese Aviation, February 11 1935, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA, p. 2; A-1-a 21684,Visit to Japan of Mr Victor E. Bertrandias of the Douglas Aircraft Company, February 16 1937, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA, pp. 1-2.
 2085-680, Aircraft Factories, June 8, 1930, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America, p. 4.
 2085-844, Aircraft Building of the Army & Navy during 1931, March 6, 1932, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America, p. 1.
 Mark R. Peattie, Sunburst: The Rise of Japanese Naval Air Power, 1909-1941 (Annapolis: Naval Institute Press, 2001), p. 27; Yoichi Hirama, ‘Japanese Naval Preparations for World War II,’ Naval War College Review, 44:2 (1991), p. 69; René J. Francillon, Japanese Aircraft of the Pacific War, Second Edition (London: Putnam Aeronautical Books, 1979), p. 31. For further details on the interwar naval arms limitation treaties, see: Erik Goldstein and John H. Maurer (eds.), The Washington Naval Conference, 1921-22: Naval Rivalry, East Asian Stability and the Road to Pearl Harbor (London: Frank Cass, 1994); John H. Maurer and Christopher M. Bell (eds.), At the Crossroads between Peace and War: The London Naval Conference of 1930 (Annapolis: Naval Institute Press, 2014).
 A-1-a 21973, Development of the Japanese Air Fleet, March 5, 1936, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA; A-1-a 21973, Japanese Naval Aviation, June 1, 1936, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA.
 A-1-a 21973, Development of the Japanese Air Fleet, 6-12.
 A-1-a 21684, British Estimate of Japanese Aviation; A-1-a 21684, British Estimate of Japanese Aviation, Continued; 2085-812, Aircraft Production – Non-Governmental. Mitsubishi Heavy Industries Company, Ltd. Nagoya Aircraft Works, June 7, 1937, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America; 2085-885, Air Information, April 28, 1934, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America; 2085-687, Reply to Evaluation of Reports, October 23, 1936, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America.
 2085-687, Reply to Evaluation of Reports, October 23, 1936, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America, p. 1.
 2085-810, Military Aviation – General, p. 1.
 A-1-a 21973, Japanese Naval Aviation, p. 5.
 A-1-a 21684, British Estimate of Japanese Aviation, p. 4.
 Mikesh and Abe, Japanese Aircraft, p. 45; Peattie, Sunburst, p. 86, 89. Also see: Francillon, Japanese Aircraft of the Pacific War.
 A-1-a 21684, British Estimate of Japanese Aviation, Continued, p. 2.
 A-1-a 21684, British Estimate of Japanese Aviation, p. 4.
 A-1-a 21684, Foreign Opinions Regarding Japanese Naval and Military Aviation, February 21, 1935, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA.
 A-1-m 15776, Fighting Experience of the Japanese Military Air Forces, March 17, 1936, Naval Attaché Reports, 1886-1939, Box 68, RG 38, NA, 6.
 2085-687, Reply to Evaluation of Reports, p. 2.
 A-1-a 21684, Visit to Japan of American Aircraft Representative, p. 1.
 A-1-a 21684, British Estimate of Japanese Aviation, Continued, pp. 1-2.
 A-1-a 21684, British Estimate of Japanese Aviation, p. 4.