Quoting the Pentagon's 2017 survey of the Chinese military, Japanese newspaper Sankei Shimbun reported June 8 the People's Liberation Army could be training for a raid of outlying areas, including the Japan-administered Senkaku Islands, also claimed by China and Taiwan.
In a section on China's amphibious capabilities, the report from the U.S. Department of Defense states the "PLA Army focuses its amphibious efforts on a Taiwan invasion while the PLA Navy Marine Corps focuses on small island seizures in the South China Sea, with a potential emerging mission in the Senkakus."
The Japanese military also may be concerned that, according to the report, China's PLA Navy Marine Corps brigades conducted "battalion-level amphibious training at their respective training areas in Guangdong," or the Southern Theater.
The Japan Maritime Self-Defense Force destroyer JS Ashigara (DDG 178), foreground, the Arleigh Burke-class guided-missile destroyer USS Wayne E. Meyer (DDG 108) and the Ticonderoga-class guided-missile cruiser USS Lake Champlain (CG 57) transit the Philippine Sea. (U.S. Navy photo by Mass Communication Specialist 2nd Class Z.A. Landers)
"The training focused on swimming amphibious armored vehicles from sea to shore, small boat assault and deployment of special forces by helicopter," the report states.
In May, Taiwan's Central News Agency reported China's Navy Marine Corps is in the process of building a 100,000-strong military unit.
The Pentagon report states China has used "coercive tactics, such as the use of law enforcement vessels and its maritime militia, to enforce maritime claims."
Article 5 of the U.S.-Japan Mutual Security Treaty applies to the Senkakus, and the United States is obligated to defend the islands if they come under attack.
In May, four Chinese coast guard ships entered Japanese territorial waters near Okinawa and the Senkaku Islands and in 2016, more than 100 Chinese ships trespassed into Japan's territorial waters, the second-largest annual number of Chinese ships entering disputed areas since Japan announced the nationalization of the Senkakus in September 2012.