In the year ending March 31 2015 Japanese fighters had to go aloft 943 times as foreign military aircraft approached Japanese airspace. This was a 16 percent increase over the previous 12 months and one short of the record (944), which was set in 1984 during the Cold War. After the Cold War ended in 1991 (when there were 488 sorties), the number of intrusions fell through the 1990s, but since 2000 have increased. These days most of the approaching aircraft are Chinese (up to 70 percent in some three month periods) and the rest Russian. But over the last six months the Russians have been more active, although the Chinese are still the majority of intrusions.
In 2013 Japanese aircraft went up over 300 times to confront Chinese aircraft (often recon aircraft) coming too close to Japanese air space. Thus 2013 was the first year Chinese intrusions exceeded Russian ones. This has been coming for several years. In 2011 nearly 43 percent of the sorties were for Chinese aircraft. That's almost three times as many Chinese intrusions as in 2010. Meanwhile Russian intrusions have been declining. As recently as 2011 Russia still accounted for 52 percent of the intrusions.
Most of the Russian incursions are recon aircraft or other aircraft types clearly on training missions. More than half the Chinese aircraft are warplanes and most are not there as part of a training exercise. Nearly all of these “incursions” stop short of actually entering Japanese airspace. The few times Japanese airspace is entered it is usually by accident and very brief.
Although Russian warplanes continue to be a nuisance off the coast Japan considers this activity much less threatening. The Russian aircraft are flying more training missions in the Pacific and the Japanese have come to understand how it is nearly impossible for Russian pilots getting out to sea without showing up on a Japanese radar or coming close to Japanese air space. That’s because there is a lot of Japanese airspace off the east coast of Eurasia, so Russian warplanes out there cannot avoid passing close to Japanese air defense radars. China does not have this problem.
These intrusions have been increasing sharply since 2008. Early on the Japanese launched many aircraft for each intrusion. For example, in 2008 a Russian Tu-95 entered Japanese airspace near an uninhabited island about 600 kilometers south of Tokyo. Although the Russian aircraft was in Japanese airspace for only about three minutes the Japanese launched 22 aircraft to intercept. This force included two AWACs aircraft and twenty fighters. No Russian aircraft entered Japanese airspace without permission again until 2013 and the Russians apologized for that one. But as the intrusions increased, the number of interceptors sent out for each incident decreased.
The Japanese believe that one cause for this increased activity is more electronic and maritime patrol aircraft are available to the Chinese who have a desire to gather as much information as possible about the strongest potential foe in the area. But the main reason is the dispute with China over the Senkaku Islands near Okinawa. China and Japan both claim these uninhabited islets, which are 320 kilometers southeast of the Chinese mainland, 167 kilometers northeast of Taiwan, and 426 kilometers southwest of Japan (Okinawa, which China also has claims on). The Senkaku Islands and have a total area of 6.3 square kilometers. Taiwan also claims the Senkakus, which were discovered by Chinese fishermen in the 16th century and taken over by Japan in 1879. They are valuable now because of the 380 kilometer economic zone nations can claim in their coastal waters. This includes fishing and possible underwater oil and gas fields.