Japan's defense expansion and postwar military constraints

China supplies the large majority of the world's processed rare-earth minerals, an input Japanese manufacturers depend on, and has historically been Japan's largest source of inbound tourists. Both have become instruments in the bilateral relationship: Chinese export licensing on rare earths and related materials to Japan has tightened at points of diplomatic friction, Chinese authorities have issued travel advisories that preceded declines in tourist arrivals from China, and imports of Japanese seafood have at times been restricted. Japanese nationals, including company employees, have also been detained by Chinese authorities. Japanese and allied governments have responded by pursuing alternative mineral sources, including seabed extraction and recycling, and joint stockpiling arrangements with other countries.

The Senkaku Islands, a small uninhabited island group in the East China Sea, have been administered by Japan since 1972 and are also claimed by China, which calls them the Diaoyu Islands, and by Taiwan. China Coast Guard vessels regularly enter the contiguous zone and, at intervals, the territorial waters around the islands; Japan's coast guard tracks these vessels and at times acts to expel them. The dispute also extends to the wider East China Sea, where the two countries' exclusive economic zone claims overlap and where survey vessels, fishing activity and gas-field infrastructure near the median line have periodically drawn protest from Japan. The islands lie near Japan's Yonaguni and Ishigaki islands, within the broader geography of the first island chain.

Japan's conduct during its wartime occupation of parts of China, including the 1937 Nanjing Massacre, the use of forced labor, and the coercion of women into wartime brothels, remains a subject of dispute between the two countries' historical accounts. Visits or ritual offerings by Japanese officials to Yasukuni Shrine, which honors Japan's war dead including convicted war criminals, routinely draw formal protest from China. Related disputes include denial or minimization of wartime events by some Japanese public figures, the restoration of wartime military rank titles, unexploded or abandoned wartime chemical weapons still being cleared in China, and calls for Japan to return cultural relics removed during the war. These disputes recur independently of the theater's other dimensions and are raised by Chinese officials and state media at points of broader diplomatic friction.