Imperial Japanese Army Air Service(IJAAS)

Japanese army aviation was organized into a separate chain of command within the Ministry of War of Japan in 1919. In May 1925, the Imperial Japanese Army Air Corps was established under the command of Lieutenant General Kinichi Yasumitsu, it was regarded as a branch equal to the artillery, cavalry or infantry, and contained 3,700 personnel with about 500 aircraft. In a reorganization of 1927-05-05, the Air Regiment ( Hiko Rentai) was created, each consisting of two battalions, with each battalion consisting of up to four squadrons. Each Air Regiment was a mixed purpose unit, consisting of a mixture of fighter and reconnaissance squadrons.
In April 1944, a reorganization of the Japanese Army Air Service occurred. Maintenance and ground service units, formerly a separate command, were merged into the Air Combat Group (Hiko Sentai). The flying squadrons of the Air Combat Group were re-designated as Squadron (Hikotai), and the ground units were designated Maintenance Units (Seibutai). In the final phase of the war, the Special Attack Units evolved into dedicated suicide units for kamikaze missions. Around 170 of these units were formed, 57 by the Instructor Air Division alone. Notionally equipped with 12 aircraft each, it eventually comprised around 2000 aircraft. The final reorganisation of the took place during preparation for Operation Ketsu-Go, the defence of the home islands in 1945 when all the Air Armies were combined under a centralised command of General Masakazu Kawabe .
Naval transports for Army Use only
Due to the poor relations between the Imperial Japanese Army and Imperial Japanese Navy, the Army found it necessary to procure and operate their own aircraft carriers for the purposes of providing escort and protection for Army transport shipping convoys. These escort/transport carriers were converted from small passenger liners or merchant ships and possessed the capacity to operate from eight to 38 aircraft, depending on type and size, and were also used to transport personnel and tanks. These vessels included 11 converted and 2 unfinished merchantmen refitted as transport carriers and were operated by civilian crews with Army personnel manning the light and medium anti-aircraft guns. Not only did they transport aircraft, but also equipment, fuel, vehicles and even troops.

After the occupation of Manchuria and Korea, Japan turned its military interests to Soviet territories. The first major Soviet-Japanese border incident, the Battle of Lake Khasan, happened in 1938 in Primorye. Clashes between Japanese and Soviet forces frequently occurred on the border of Manchuria. In 1939, Manchuria was a puppet state of Japan, known as Manchukuo. The Japanese maintained that the border between Manchukuo and the Mongolian People's Republic was the Khalkhin Gol, which flows into Lake Buir. In contrast, the Mongolians and their Soviet allies maintained that the border ran some 16 kilometres (10 miles) east of the river, just east of Nomonhan village. The principal occupying army of Manchukuo was the Kwantung Army of Japan, consisting of some of the best Japanese units in 1939. However, the western region of Manchukuo was garrisoned by the newly formed IJA 23rd Division at Hailar, under General Michitaro Komatsubara and included several Manchukuoan army and border guard units. Soviet forces consisted of the 57th Special Corps, forward deployed from the Trans-Baikal Military District, responsible for the defence of the border between Siberia and Manchuria. The Mongolian troops mainly consisted of cavalry brigades and light artillery units, and proved to be effective and agile, but lacked armour and manpower in sufficient numbers. The Incident went from the 11th of May 1939 till the 16th of September 1939. With the truce signed, Stalin turned back west to finsih the invasion of Poland with the Germans, knowing that his eastern provinces were secure from further Japanese incursions. All up the losses were approximately 249 Soviet aircraft and Japanese somewhere between as low as 50, but as high as 156. It was mainly through superior Japanese tactics which gave the IJAAS the edge. The aircraft used by the Soviets were mainly TB-3 heavy bombers, SB-2 medium bombers, R-5 light bombers plus I-15s, I-153s and I-16s fighters and DC-3 transports while the Japanese used Ki-10 light bomber, BR.20, Ki-21 medium bomber and Ki-27 fighters.
The IJAAS had trained only 1,700 pilots in 30 years; losses at Nomonhan crippled it. By December 1941 Army flight schools were graduating only 750 pilots a year.

Japan, although seemingly advanced in aerial tactics, entered the war with a narrow aerial doctrine, insufficient numbers of aircraft and those of generally poor design (excluding the Ki-43, of course), too few aircrews and inadequate logistics for a war of attrition. Neither its army nor its naval air arm was prepared for the duration, violence or sophistication of the war to come. Even its short-lived lead in aerial tactics collapsed once the Guadalcanal campaign began. Completely aside from having an industrial base able to produce enough aircraft, a nation's air force needs to be balanced between aircraft, combat and maintenance crews, and air bases. If Japan was to seize an empire, its airfield builders would have to accompany the fighting forces every step of the way. Absent of such construction units, the IJAAS would have to use captured bases. The Army's piecemeal commitment of aviation maintenance units was due to the original absence of any strategic plans to put large army forces into the Southwest Pacific. Rising air losses in the Solomons, however, led the Navy to request that the Army bring in aircraft. But without a clear long-range plan or doctrine of what to do, no one could arrange the necessary logistical support. Depots where engines could be changed and major repairs made were few and scattered. The Fourth Air Army's heavy equipment for engine changes and major structural repair on New Guinea, for instance, was poor. Periodic inspections, repairs, overhauls and even routine servicing fell off because of maintenance shortfalls. The Japanese had to abandon many aircraft during advances or retreats that easily could have been repaired at rear areas. Poor repair also denied them the opportunity to use worn-out aircraft in a training role. Because the Army and Navy did not cooperate, Army aircraft in New Guinea had to fly 1,500 miles to Manila for engine changes even though the Navy had major maintenance assets as close as Rabaul. Even at Rabaul, aircraft maintenance was so limited that of 60 fighters and 40 bombers that might be on hand, only a mix of 30 typically could fly on a given date. To say that the Japanese Army and Navy did not cooperate on aerial matters would be a serious understatement. "They hated each other," Lt. Cmdr. Masataka Chihaya recalled, "[they] almost fought. Exchange of secrets and experiences, the common use of airplanes and other instruments, could not even be thought of."

By 1941, the Japanese Army Air Service had about 1,500 combat capable aircraft. These aircraft were spread from Japan, to China, to Burma, and all through South East Asia. During the first years of the war, Japan continued technical development and deployment of increasingly advanced aircraft and enjoyed air superiority over most battlefields due to the combat experience of its crews, plus the low numbers and lack of preparation of the Allied forces. However, by 1944, with most of the supplies and oil coming from far flung conquests being sunk more than reaching Japan, it wasnt long before all services were hard pressed to get sufficient fuel for defence, let alone training pilots. At the time of the Battle of Leyte Gulf the Army would not release sufficent oil for the Navy to be able to move at battle speed when necessary. By 1945, after the invasion of Iwo Jima, came the invasion of Onkinawa. This was where the Allies would meet the last of the IJNAS and IJAAS in battle. The 'Kamikaze'(Divine Wind). Towards the end of its existence the IJAAS and IJNAS resorted to kamikaze attacks using pilots who had rudimentary training and little or no flight experience. They were escorted by the last surviving experienced pilots to the attack points and left ot their fate. One can only speculate how many kamikazes would have been available if the Allies had invaded Japan proper.

Following the defeat at the end of World War II the Imperial Japanese Army and Navy were dissolved. Little was done in the way of rebuilding Japan as money was poured into Europe, with the threat of Communism hanging over the West. It was not until the Korean Conflict with the invasion of South Korea by North Korea in June 1950 that Japan became the focus of investment as the Military used Japan as a staging base for air support as well as thousands of troops pouring in as replacements for ground forces in Korea. The USAF used many bases in Japan for escort and ground support in the early stages of the invasion, right up to the Pusan perimeter. At the end of the Korean War, it was realised that Japan was needed as a bulwark against any further aggression by Chinese, Koreans and Russians building bases to spread Communism throughout the Pacific. From this, the Japanese Self-Defense Forces(JSDF) came into existence, with the passing of the 1954 Self-Defense Forces Law with the Japanese Air Self-Defense Force (JASDF) as the aviation branch. JASDF also provides air support for ground and sea operations of the JGSDF and the JMSDF and air defense for bases of all the forces. Although support fighter squadrons started being modernized in 1989, they lacked precision-guided weapons for support of ground operations and attacks on hostile ships, and JASDF pilots receive little flight training over oceans to prepare for maritime operations. Base defenses were upgraded in the late 1980s with new surface-to-air missiles, modern antiaircraft artillery and new fixed and mobile aircraft shelters.