Overview

Japan states that there is no territorial dispute over the Senkaku Islands and that they are an inherent part of Japan’s territory under international law. China calls them Diaoyu and claims they were taken by Japan during imperial expansion. The United States holds a neutral position on sovereignty but affirms that the islands are under Japanese administration and therefore fall within Article 5 of the U.S.–Japan Security Treaty.

This places the Senkaku Islands squarely inside the First Island Chain — the defensive arc Washington uses to constrain Chinese naval expansion and preserve stability across the East China Sea and the Taiwan Strait.

Japan’s Position

According to Japan’s Ministry of Foreign Affairs, the Senkaku Islands were terra nullius before being incorporated into Okinawa Prefecture in 1895. Tokyo argues China only began claiming the islands in the 1970s after surrounding waters were found to contain potential energy resources.

Japan stresses it exercises valid administrative control today through fisheries regulation, lighthouse upkeep and Japan Coast Guard patrols. Official MOFA language asserts: “There exists no issue of territorial sovereignty to be resolved concerning the Senkaku Islands.”

China’s Position

China says historical navigation records and maps prove the islands were traditionally part of Chinese maritime activity. Beijing condemns Japanese administrative control and regularly sends coast guard vessels into the area to challenge Japan’s claims.

U.S. Position and First Island Chain Deterrence

The United States does not declare who ultimately owns the islands, but it has repeatedly affirmed that because Japan administers them, any armed attack would trigger Article 5 of the U.S.–Japan Security Treaty.

Successive U.S. presidents — Barack Obama, Donald Trump, Joe Biden — have explicitly stated this. The Pentagon frames the islands as strategically essential positions anchoring the First Island Chain, enabling surveillance, rapid response and deterrence against PLA expansion.

Alliance Operations

U.S. Marines and Japan Self-Defense Forces conduct joint island-defense drills, deploy anti-ship missiles, and integrate radar networks from Okinawa through the Ryukyu chain. These efforts reinforce that the First Island Chain — including the Senkakus — forms an interlocked defensive line against coercion.

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