Gray Zone Warfare in the East China Sea: The Threat of Chinese Maritime Militia and Japan's Response

In March 2026, a large-scale military operation by Chinese fishing fleets is unfolding in the East China Sea. From December 24 to 26, 2025, over 2,000 vessels formed a reverse L-shaped formation spanning 470 kilometers. Subsequently, in January and March 2026, fleets of more than 1,000 vessels engaged in similar actions, with some crossing the Japan-China median line into Japanese waters. The majority of these vessels are dispatched from Zhejiang Province, with 200 to 300 participating each time.

Under the Japan-China fisheries agreement, such actions are not illegal as long as they are considered fishing activities. However, this does not explain their intent. Why are thousands of vessels repeatedly aligning over hundreds of kilometers? If these are not ordinary fishing boats but maritime militia, it poses a serious security challenge for Japan and the entire region.

Article 22 of China's National Defense Law defines militia as part of the armed forces alongside active-duty troops, reserve forces, and the People's Armed Police. According to Chinese sources, fishermen and crew members are subject to conscription and typically engage in civilian livelihoods, but can be mobilized to support the military or the Coast Guard as needed. They are said to receive regular political education and training, and the aforementioned formations are believed to reflect such organized activities.

While activities in the South China Sea are the most well-known, maritime militia have also expanded into the East China Sea and the Yellow Sea. Since around 2013, trial programs have been initiated in Zhejiang Province, establishing militia units in cities such as Ningbo, Wenzhou, and Taizhou. This coincides with the period when the protection of maritime interests was elevated to a central priority for the party, state, and military.

Maritime militia personnel occupy a deliberately ambiguous position. They are both civilians and quasi-military entities. As noted by Connor M. Kennedy of the U.S. Naval War College, this duality allows China to operate effectively in the gray zone between peace and conflict. Currently, such units are organized along much of China's coastline, and countries along the first island chain, including Japan, face ongoing challenges from gray zone tactics based on maritime militia.

The Xi Jinping administration's efforts to organize maritime militia across the coastal areas should be understood as part of a broader strategy supporting military expansion into the Pacific. In June 2025, China deployed two aircraft carriers simultaneously to the Pacific for the first time. According to Japan's Joint Staff Office, one of them, the Liaoning, operated approximately 990 kilometers south of Okinotorishima, near the exclusive economic zone of Yap State in the Federated States of Micronesia, close to Palau.

China is currently preparing to exert pressure on Taiwan not only from the mainland but also from the Pacific, attempting to deny U.S. access in the waters between the first and second island chains. To maintain such a strategy, China must secure its rear, meaning it needs to constrain the activities of Japan's Maritime Self-Defense Force and Coast Guard in the East China Sea. If maritime militia can disrupt or delay the movements of Japan's Coast Guard and Maritime Self-Defense Force, Beijing can more effectively assert control over these waters.

In this sense, maritime militia are not merely coastal forces but elements supporting China's broader efforts to blockade key straits and waters. This could weaken deterrence along the first island chain and shift the regional balance in favor of China.

Having demonstrated the ability to mobilize thousands of fishing vessels, Japan must urgently assess the implications and recalibrate its responses. So, what should it be wary of?

First, large-scale fishing fleets complicate the Japan Coast Guard's ability to patrol territorial waters around the Senkaku Islands. There is a precedent. In 2016, 200 to 300 Chinese fishing vessels gathered near the Senkaku Islands, after which Coast Guard vessels repeatedly intruded into Japanese territorial waters. A decade later, the scale could be much larger. The Coast Guard maintains a constant presence with patrol vessels of around 1,000 tons, but in future incidents, thousands of vessels may operate in coordination with the Coast Guard.

Second, China is creating an asymmetric dynamic by framing the situation as fishermen versus warships or fishermen versus government vessels. This allows it to gain an advantage in both the physical and information domains. In 2009, Chinese maritime militia vessels interfered with the U.S. Navy's surveillance ship Impeccable in the South China Sea, attempting to disrupt its operations. The same logic applies to cognitive warfare. Beijing can portray Japan's patrol vessels as "harassing civilian fishing boats," positioning law enforcement actions as state aggression. Such narratives have been repeatedly deployed in the South China Sea and could be replicated around the Senkaku Islands or during a Taiwan crisis.

Third, there is the potential for a "high-tech people's war." Xi Jinping is currently adapting Mao Zedong's concept of mass mobilization through the integration of maritime militia and new technologies. Reports indicate that these units are receiving training in operating unmanned systems. In times of crisis, there is a possibility of deploying large numbers of autonomous underwater vehicles (AUVs) for reconnaissance and sabotage, including attacks on undersea cables. Chinese documents also suggest that these highly mobile units may undertake electronic warfare activities, such as jamming.

China is likely to deepen the coordination between maritime militia and the Coast Guard in the East China Sea. Japan must reaffirm its strategy to address the gray zone challenges posed by such coordination without being overshadowed by military emergencies surrounding Taiwan.

The rapid development of missile capabilities in East Asia is also transforming the security environment in the region. Despite constitutional constraints, Japan has confirmed the development of hypersonic glide vehicle (HVGP) systems, planning to deploy them between 2026 and 2027. The initial version is said to have a range of about 1,000 kilometers, with future extensions aimed at 3,000 kilometers. Additionally, an improved version of the Type 12 anti-ship missile is expected to reach a range of 1,200 kilometers and is slated for deployment in Japan's island territories within the next few weeks to months. This has already provoked strong backlash from China.

South Korea is developing missile technology without political constraints, and the Hyunmoo-5 is gaining attention as one of the world's most powerful non-nuclear missiles. Weighing 36 tons with an 8-ton warhead and a range of 3,000 kilometers, it is nicknamed the "bunker buster." The first transportable launch system was unveiled on October 1, 2024.

Taiwan does not possess independent launch capabilities but is actively developing anti-ship missiles. A new domestically produced long-range anti-ship missile with a range of 600 to 1,000 kilometers is currently under development, with the primary goal of penetrating the Chinese fleet's air defense network and neutralizing its combat power before it approaches Taiwan.

These missile programs indicate that technological prowess, alliance structures, and threat perceptions are converging to reshape the military balance in East Asia. Each country and region is advancing along its own trajectory, yet all are responding to the same strategic environment defined by the growing capabilities of China and North Korea, as well as a broad security framework centered around the United States.

The combination of longer ranges, faster systems, and greater operational flexibility expands the range of military options available to decision-makers while compressing response times and increasing the risk of miscalculation. Under such conditions, even limited confrontations carry the risk of rapid escalation, as the underlying technological foundation enables swift transitions between deterrence and active military engagement.

The U.S.-Japan alliance serves as a crucial foundation for addressing this increasingly complex threat environment. The annual threat assessment report from the U.S. intelligence community, released on March 25, 2026, evaluates that North Korea continues to expand its nuclear and conventional capabilities, sometimes with Russian support, enhancing its ability to disrupt U.S. networks and critical infrastructure. The 2026 report emphasizes the threat posed by North Korea's cyber capabilities more than the 2025 version, characterizing these capabilities as "sophisticated and agile."

North Korea is also increasing its foreign currency reserves through military and economic cooperation with Russia. According to estimates from South Korea's National Security Research Institute, North Korea has generated up to $14.4 billion in revenue since August 2023 through arms sales and troop deployments. Of this, $620 million is said to have come from four troop deployments, while $7.05 billion to $13.78 billion is attributed to arms sales. The deepening relationship between North Korea and Russia enables the acceleration of military development while offsetting the economic difficulties caused by international sanctions.

The security environment in East Asia, from the East China Sea to the Korean Peninsula and the Taiwan Strait, is rapidly transforming. The gray zone tactics of China's maritime militia, the expansion of missile capabilities among regional countries, the increasing cyber threats from North Korea, and the deepening military cooperation with Russia—all of these factors are intricately intertwined, forming a new strategic reality. Japan must strengthen its defense capabilities and build a multi-layered deterrent posture while maintaining close cooperation with its allies in this changing environment. A flexible strategy capable of addressing threats at all levels, from gray zones to high-intensity conflicts, is required.