China Coast Guard vessel enters Japan's EEZ; Tokyo says crew claimed 'routine patrol'

June 9, 2026 — The Japanese Asahi Shimbun reported that a China Coast Guard (CCG) vessel was observed navigating within Japan's exclusive economic zone (EEZ) south of Yonaguni Island in Okinawa Prefecture, according to a press conference held by Chief Cabinet Secretary Kihara Minoru on the same day.

Kihara stated that the CCG vessel was detected by a Japan Coast Guard (JCG) patrol vessel. When the JCG queried the vessel, it responded that it was conducting a "routine patrol" and asserted Chinese exercise of jurisdiction over the area.

China's Response

At a regular press conference on June 9, Chinese Foreign Ministry spokesperson Lin Jian confirmed that the CCG vessel had been "conducting patrols in accordance with the law." He further stated:

"Japan and the Philippines bypassing China to initiate the so-called maritime delimitation talks constitutes a severe violation of UNCLOS and other international laws and basic norms governing international relations. It also seriously infringes on China's maritime rights and interests. China will by no means accept this."

Broader Context of Chinese Activities

China has long made claims in Asian waters that are not grounded in the United Nations Convention on the Law of the Sea (UNCLOS). Since June 2026, China has been conducting "marine scientific research" (MSR) and patrols in accordance with Chinese domestic laws in Japan's EEZ south of Yonaguni Island and east of Taiwan.

The situation in these waters appears to be shifting from China merely asserting claims to a new phase of carrying out concrete activities — a gradual accumulation of facts on the water, similar to what has occurred in disputed parts of the South China Sea. The commencement of negotiations to delimit the maritime boundary between Japan and the Philippines has provided China with an "excuse" to advance to this new phase.

Legal Analysis

Marine Scientific Research

Chinese MSR conducted in Japan's EEZ without Japanese consent violates UNCLOS and constitutes a breach of international law.

CCG Patrols

CCG "patrols" in Japan's EEZ are more complex and may not immediately be regarded as violations of international law.

Unlike territorial waters, coastal states possess sovereign rights and jurisdiction only over specific matters in the EEZ. The EEZ regime was created primarily to pursue the economic interests of coastal states.

• Article 56 (1) of UNCLOS stipulates the sovereign rights of coastal states over natural resources in the EEZ and places them at the core of the EEZ regime. It also grants coastal states jurisdiction over:
• Marine scientific research
• The establishment and use of artificial islands, installations, and structures
• The protection and preservation of the marine environment

An EEZ is a maritime area where coastal states are granted sovereign rights and jurisdiction over what was conventionally considered high seas. Except for the specific matters stipulated by UNCLOS, those areas retain the characteristics of high seas.

• Article 58 (1) of UNCLOS states that all countries enjoy the "freedoms of navigation and overflight" within the EEZ. The same article stipulates that the freedoms enjoyed by ships (including warships and other government vessels) are equivalent to the "freedom of the high seas" as stipulated in Article 87 (1) of UNCLOS.

• Article 58 (3) stipulates that any state is obliged under the EEZ to: "In exercising their rights and performing their duties under this Convention in the exclusive economic zone, States shall have due regard to the rights and duties of the coastal State."

Implications for Government Vessels

Warships and other government vessels can exercise enforcement jurisdiction over their own vessels according to the flag state principle on the high seas. However, when exercising such jurisdiction within a country's EEZ, they are obliged to have "due regard" to the sovereign rights and jurisdiction of the coastal state of that EEZ.

The inclusion of the obligation to have "due regard" in Article 58 (3) of UNCLOS was a result of adjustments made during the convention drafting process. However, there remains ambiguity regarding which activities of non-coastal states in an EEZ may or may not be considered to fulfill this obligation.

Actions that fail to "have due regard" to the sovereign rights and jurisdictions of EEZ coastal states include, among other things:

1. Obstructing the exercise of sovereign rights by EEZ coastal states for exploration, development, conservation, and management of natural resources
2. Obstructing the exercise of sovereign rights by EEZ coastal states for creating and using artificial islands, facilities, and structures

Japan's Next Steps

Japan must carefully examine, analyze, and evaluate the specific contents of the CCG's patrols conducted in the Japanese EEZ south of Yonaguni Island and east of Taiwan — including the purpose of those patrols and the Chinese domestic laws they purport to enforce — and respond accordingly.