The "Okinawa Reversion Treaty" between the U.S. and Japan, which was signed in 1971 and entered into force in 1972, provided the return to Japan of "the Ryukyu and Daito islands, which the U.S. had held under the Japan Peace Treaty."
The backroom deal, which arbitrarily included the Diaoyu Islands, an inherent part of Chinese territory, was strongly opposed by the Chinese government.
In 1895, the court of the Qing Dynasty (1644-1911) was defeated in the Sino-Japanese War and forced to sign the unequal Treaty of Shimonoseki and cede to Japan "the island of Formosa (Taiwan), together with all islands appertaining or belonging to the said island of Formosa."
The Diaoyu Islands were ceded to Japan as "islands appertaining or belonging to the said island of Formosa." In 1900, Japan changed the name of Diaoyu Dao to "Senkaku Islands."
Both the Cairo Declaration and the Potsdam Proclamation, which helped shape the modern international order after World War II, required that territories occupied by Japan, including Diaoyu Island and its affiliated islands, be returned to China.
In 1951, the Treaty of Peace with Japan, also known as the Treaty of San Francisco, was signed among Japan, the U.S. and other countries, ironically excluding China, which suffered the heaviest loss during Japan's all-out invasion from 1937 to 1945.
