Four Chinese Coast Guard Vessels Appear Near Senkaku for 330 Consecutive Days, Pressuring Japan's Maritime Security

The Eleventh Regional Coast Guard Headquarters confirmed that four vessels from the China Coast Guard, equipped with machine guns, were involved. In late June, these ships entered the contiguous zone around the Senkaku Islands and were warned by Japanese patrol boats not to approach territorial waters. According to Newsweek, the confirmation of Chinese government vessels has reached 330 consecutive days, indicating that this is not a one-off show of force but has entered a stage where it should be treated as a nearly normalized pressure.

The Senkaku Islands are effectively controlled by Japan, while China claims sovereignty over them as the Diaoyu Islands. In an updated explanation on June 3, the Japanese Ministry of Foreign Affairs organized that Chinese Coast Guard vessels enter the contiguous zone almost daily, with incursions into territorial waters occurring several times a month. Furthermore, actions including the approach of armed vessels and Japanese fishing boats are positioned as attempts to unilaterally change the status quo through force or intimidation.

The Significance of the Number 330

The contiguous zone is the maritime area extending from 12 nautical miles to 24 nautical miles outside territorial waters, and the mere presence of foreign vessels does not immediately render it illegal. However, when government vessels are continuously deployed in the same area for an extended period, sometimes in combination with armed ships, the boundary between law enforcement activities and military pressure is intentionally blurred. This is the crux of the issue.

From the perspective of the Japan Maritime Self-Defense Force, this is not a prelude to a fleet battle. Rather, it is an operation that exhausts daily vigilance, information sharing, and political decision-making among the Japan Coast Guard, the Ministry of Foreign Affairs, the Ministry of Defense, and the Self-Defense Forces. During the Cold War, the Soviet Navy approached with clear warships, but today, China divides roles between the Coast Guard and the Navy. If we separate capability and intent, the capability is already sufficient, and the intent appears to be to prolong low-intensity pressure.

Implications for the Japan-U.S. Alliance

The United States has repeatedly confirmed that the Senkaku Islands fall under the application of Article 5 of the Japan-U.S. Security Treaty. However, this confirmation serves as a deterrent in the event of an armed attack and does not automatically stop daily incursions into the contiguous zone. What China aims for is likely to exhaust Japan's on-site response below the threshold for treaty activation.

For this reason, what Japan needs is not a flashy deployment of Maritime Self-Defense Force escort ships, but a sustainable surveillance capability that connects Coast Guard patrol vessels, aircraft, drones, coastal radar, and satellite information. It is meaningless if the Air Self-Defense Force's alert control, the Maritime Self-Defense Force's P-1 patrol aircraft, and the Ground Self-Defense Force's deployed units in the southwestern islands are each seeing a different picture. The mechanism that connects with U.S. military ISR (Intelligence, Surveillance, and Reconnaissance) should be tested not only in times of crisis but also in peacetime gray areas.

The Dangers of Excessive Militarization

In my view, the most important thing to avoid in responding to the Senkaku situation is hastily replacing the Coast Guard's mission with that of the Self-Defense Forces. Since China is putting its Coast Guard at the forefront, if Japan responds militarily from the outset, it could provide Beijing with a pretext for escalation. What is needed is not a weak stance, but a two-layer structure that maintains the face of law enforcement while ensuring solid support from the Self-Defense Forces and the alliance behind it.

In the confrontation between Japanese and Chinese vessels reported by the BBC at the end of last year, the safety of Japanese fishing boats and demands for the withdrawal of Chinese vessels were made simultaneously. Such on-site measures may seem understated, but they are, in fact, at the forefront of sovereignty management. The number of 330 consecutive days indicates that China is operating the Senkaku not as a temporary diplomatic card, but as a routine pressure device.

Overlooked Human Burden

Finally, I want to emphasize that it is the personnel, not the equipment, that matters. Patrol vessels and aircraft cannot operate without crew and maintenance staff. As the number of consecutive days increases on the Chinese side, the Japanese side is forced to respond without rest. The real risk lies not in a sudden major clash one day, but in the fatigued personnel making small judgment errors over time. The defense line for the Senkaku exists not only on nautical charts but also within duty rosters.

Main references: Newsweek, BBC, explanations related to the Senkaku Islands from the Japanese Ministry of Foreign Affairs, and materials on Chinese military trends from the Japanese Ministry of Defense.