Senkaku Islands

The Senkaku Islands form a small, uninhabited archipelago in the southern East China Sea, roughly northeast of Taiwan and west of Okinawa’s Ishigaki Island.¹ Japan counts five islands and three smaller rocky features; the largest is Uotsuri Island. The islands have no permanent population, fresh-water infrastructure, or established civilian economy, but their surrounding waters support fishing and have strategic value.

The same features are called the Diaoyu Islands in the People’s Republic of China and the Diaoyutai Islands in Taiwan. These names are not merely linguistic alternatives: each government uses its preferred name in official maps, legislation, and diplomatic statements. The archipelago lies near sea lanes connecting the East China Sea with the western Pacific, while its position affects maritime boundaries involving Japan, China, and Taiwan.

The sovereignty dispute rests on competing readings of historical records and the legal consequences of Japan’s nineteenth-century expansion. Japan states that it surveyed the islands in the late nineteenth century, found them terra nullius, and incorporated them into Okinawa Prefecture in January 1895 before the Treaty of Shimonoseki ended the First Sino-Japanese War.² China and Taiwan argue that Chinese sources and maps demonstrate earlier discovery, naming, and administration, and that the islands were taken as part of territories ceded after that war.

After the Second World War, the United States administered the islands with the Ryukyu Islands under the postwar settlement. The 1971 Okinawa Reversion Agreement returned administrative rights over the Ryukyus to Japan in 1972, including the Senkaku Islands as understood by the United States, while Washington stated that the agreement did not determine ultimate sovereignty.³ That distinction remains central to the dispute.

Japan has exercised effective administrative control since the reversion, and it treats the islands as part of Okinawa Prefecture rather than as a territory requiring bilateral negotiation.² Japan maintains that no sovereignty dispute exists, while China and Taiwan reject that position and assert their own territorial claims. Taiwan’s claim is administratively distinct from the People’s Republic of China’s claim, although both use related historical arguments.

The United States does not take a position on the ultimate sovereignty of the islands, but it recognizes that they are under Japan’s administration and has said that the U.S.–Japan security treaty applies to territories under Japanese administration. That position separates treaty coverage from endorsement of Japan’s legal title. Under the United Nations Convention on the Law of the Sea, sovereignty over land features and the maritime zones generated by qualifying islands are related but legally separate questions.⁴

The dispute intensified after the islands’ surrounding waters became associated with potentially valuable fisheries and petroleum prospects identified in the late twentieth century.¹ In 2012, the Japanese government purchased three privately owned islands from their Japanese owner, describing the move as a means of maintaining stable administration; China condemned the purchase and announced further maritime patrols. The episode produced a sharp increase in encounters involving government vessels.

Most confrontations occur at sea rather than on the islands themselves. Chinese maritime law-enforcement vessels regularly enter waters Japan regards as territorial, while Japan’s Coast Guard monitors and warns them; Taiwan has also dispatched fishing and government vessels. Fishing activities, temporary landings, nationalist demonstrations, and aircraft or vessel patrols can therefore carry significance beyond their immediate practical purpose. The islands’ lack of permanent residents has not reduced their strategic importance because control of the features bears on navigation, resource access, and the broader balance of power in the East China Sea.

terra nullius

A territory regarded in international law as belonging to no state at the time of claimed occupation.

effective administration

The continuing exercise of governmental authority over territory, distinct from a final judicial determination of sovereignty.

exclusive economic zone

A maritime zone extending up to 200 nautical miles in which a coastal state has specific resource-related rights under the law of the sea.

Uotsuri Island

The largest island in the Senkaku archipelago, also called Diaoyu Island in Chinese usage.