Elements of the dispute include a Ming Dynasty map, a US treaty, and a fish factory. The following is a basic breakdown.
What is Japan's claim?
Japan's foreign ministry cites surveys in 1885 confirming they were "uninhabited" with "no trace of having been under the control of China." The government of Japan in January 1895 decided to incorporate the islands and to place a marker on one of them declaring them to be part of Japan.
But what do the Japanese say to the Chinese claim that the islands appear on Ming Dynasty maps?
Neither the Communist government that had taken over the Chinese mainland in 1949 nor the "Nationalist" Chinese government, driven to the island province of Taiwan, objected when the San Francisco Peace Treaty of 1951 placed the islands under US administrative control.
Why were the Americans in charge?
US forces drove the Japanese from the island prefecture of Okinawa in June 1945 in the worst Pacific battle of World War II. The islands, 220 miles southwest of Okinawa, had been governed by Okinawa under the Japanese.
When did the Chinese begin to state their claims?
The governments in Beijing and Taiwan got interested in 1970 after a United Nations study showed there might be oil and gas in the seabed around the islands. The island cluster is 76 miles from Taiwan, 92 miles from the closest Japanese island, also a part of Okinawa prefecture, and 100 miles from the coast of China.
When did Japan resume governing the islands?
Japan regained governing control in 1972 under the "reversion" of Okinawa to Japan. Since then, Japanese Coast Guard boats have been on regular patrol to prevent intrusion, mostly by Chinese fishing boats.
If Japan is so confident of its control, why do Japanese authorities keep visitors off the islands?
Japan is eager to tamp down the controversy, to retain control over the islands and surrounding waters but not to incite China.