According to Kyodo news agency of Japan, the first ship of Japan’s new generation of large whale diesel electric attack submarine, the “big whale”, has been successfully launched at the Kobe shipyard of Mitsubishi Heavy Industries. The boat is expected to be put into service in March 2022. By then, the number of submarines of Japan’s Maritime Self Defense Force will reach 22, basically realizing the expected target set by the Ministry of defense. As early as in the 2010 version of the outline of defense plan, Japan proposed to increase the number of existing submarines from 16 to 22 on the grounds of protecting national interests and “responding to possible threats”. In this regard, Japan’s defense ministry adopted the strategy of “consolidating the old and supplementing the new”. On the one hand, the service time of tide friendly submarine is extended from 18 years to 24 years. On the other hand, we should accelerate the construction of new submarines represented by Canglong class and whale class. After the “big whale” is put into service, it will form the core elements of the future underwater power of Japan’s maritime self defense force, together with the 10 Pro tide class submarines and 11 Canglong class submarines. According to the official data of Japan, the newly launched “Dajing” submarine is 84 meters long and 9.1 meters wide, with a standard displacement of 3000 tons and a crew size of 70. “Dajing” submarine will use a new lithium battery propulsion system to replace the traditional lead-acid battery, and its underwater navigation time is much longer than the current Canglong class record of about two weeks. The launch of “Da Jing” indicates that the lithium battery technology has been relatively mature and meets the requirements for large-scale submarine equipment. In addition, by removing many components from the traditional diesel electric submarine system, the underwater acoustic characteristics of the “Da Jing” submarine will be further weakened, and the difficulty of monitoring and tracking the opponent will be increased simultaneously. In terms of firepower, the “big whale” submarine will be equipped with the same level of weapon system as Canglong class. It is reported that six 533 mm torpedo tubes will be installed in the bow of the boat to launch the US made mk-37 torpedoes, Japanese 89 type heavy torpedoes and agm-84 “harpoon” anti-ship missiles, with a total carrying capacity of 30. < / P > < p > in recent years, Japan has repeatedly made high-profile announcements on the activities of its submarines in the waters around the Asia Pacific region. For example, recently, Japan’s Maritime Self Defense Force submarines and surface ships such as the “Kaga” helicopter carrier and the “Lei” destroyer formed a joint task force to conduct joint exercises in the important waters of the Asia Pacific region, and then visited the Vietnamese port of kinlan Bay. Analysts pointed out that Japan’s strategic intention mainly covers two aspects. One is to strengthen one’s sense of existence in the important Asia Pacific sea areas by means of anti submarine exercises, so as to realize “all-round and three-dimensional” intervention in the air, on the surface and under the water. Second, in line with the strategic layout of the United States, India and the Pacific, and taking maritime security as the traction, we should enhance defense cooperation with key countries in the region. It is reported that Japan and Vietnam are expected to sign a bilateral defense equipment and technology transfer agreement in the near future. Once an agreement is reached, Japan may export a series of maritime reconnaissance and surveillance equipment to Vietnam. In July this year, Japan agreed to sell six patrol boats worth $350 million under a loan agreement signed with Vietnam. < / P > < p > while frequently publicizing the trends of submarine construction and activities, Japan has gradually upgraded its efforts to attract and support relevant countries in the Asia Pacific region, which is bound to increase doubts about Japan’s regional strategic intentions, and the maritime security situation in the Asia Pacific region will also face greater uncertainty.