Background

Both China and Japan have made historical claims to sovereignty over the Senkaku/Diaoyu islands. Japan dates its control over the islands to 1895, when the government claimed the territory on the grounds that the islands were uninhabited—belonging to no one. For a number of years, a Japanese family privately owned the islands. After Japan was defeated in World War II, the country was occupied from 1945 to 1952 by the United States, which administered the islands. The United States retained control of the islands even after the end of its occupation of Japan because of their strategic value as military bases.

In 1969, the islands attracted attention when a geological survey revealed that they likely sit atop vast oil and gas reserves. Then, in 1971, as the United States was negotiating the return of the islands to Japan, both China and Taiwan began publicly issuing claims of ownership. Despite these declarations, President Richard M. Nixon concluded the agreement and gave control back to Japan. 

China’s claim argued that Japan illegally annexed the islands during the Sino-Japanese War of 1894–95. Therefore, the islands should have been returned after World War II, when the Allied powers determined that Japan had to return all the territories it had taken from China. China has dated its sovereignty over the islands to the fourteenth century. China has also provided documents and maps to support this claim. Chinese officials have also described the islands as historically critical to their defenses, shielding China from attacks by the Japanese and other parties.

Taiwan made a similar claim that Japan illegally seized the islands 1895 and that they should have been returned after World War II. Taiwan argued that when the islands were seized, they were considered a part of its territory. When Japan was ordered to return Taiwan’s occupied territory in 1945, both the mainland and Taiwan belonged to the Republic of China. However, in 1949, the Chinese civil war led to a division of the country, during which the Communist Party established the People’s Republic of China on the mainland and the government of the Republic of China fled to what is today Taiwan. China claims that Taiwan is a part of its territory, but Taiwan considers itself a separate country and argues that its control over the islands should have been restored following World War II.
 
Although the United States transferred control of the islands to Japan, it stayed neutral in the dispute that followed. Washington has stated that “a return of administrative rights over those islands to Japan, from which the rights were received, can in no way prejudice any underlying claims . . . nor can the United States, by giving back what it received, diminish the rights of other claimants.” 

Despite their disagreements over the islands, China, Japan, and Taiwan each tried to minimize the effects of the dispute on their overall relations. Although China challenged Japan over the islands in the early 1970s, the two countries still successfully negotiated a Treaty of Peace and Friendship in 1978. The two countries became increasingly interdependent trading partners as reforms over the 1980s and 1990s transformed China’s economy and opened the country to global commerce. Taiwan also continued to assert its sovereignty over the islands but maintained close economic and political ties with Japan. 

Tensions flared in 2010, when a Chinese fishing boat collided with Japanese coast guard vessels near the islands. The Japanese detained the captain of the Chinese vessel for more than two weeks. The Japanese charged the Chinese captain with obstructing the coast guard’s official duties. China retaliated by temporarily halting exports of critical materials used in Japan’s high-tech manufacturing industry. Chinese authorities also arrested four Japanese businessmen, accusing them of spying on a Chinese military installation. Japan and China soon resolved this initial flare in tensions. Japan released the captain and China agreed to release the detained businessmen. Nonetheless, the dispute remained a sensitive issue in both countries.

The issue continued to cause friction between China and Japan. In 2013, Japanese Prime Minister Shinzo Abe stated that his country would “expel by force” any Chinese landing on the islands. The next day, a Chinese spokesperson responded by labeling the islands a “core interest.” China had typically used the term core interest only to describe regions it would supposedly defend by force, such as Taiwan, Tibet, and Xinjiang. Later that year, China announced a new ADIZ over the East China Sea, an area that included the disputed islands.

China and Japan both continued to send their aircraft and naval vessels into the area, in the following years. Yet political leaders in Beijing and Tokyo have also recognized the danger inherent in this increasing military interaction. Chinese President Xi Jinping and Japanese Prime Minister Abe met in November 2014, agreeing to resume various diplomatic talks, including over natural resources in the East China Sea. The two leaders have met repeatedly since, but tensions remain high.