Japan Self-Defense Forces' First Participation in Balikatan Exercises and the Threat of Blocking the First Island Chain: A Turning Point in Northeast Asian Maritime Security

From April 20 to May 8, 2026, the U.S.-Philippines joint military exercise "Balikatan" will be conducted, and it has been announced that Japan's Self-Defense Forces will deploy approximately 1,400 personnel to participate for the first time in a proactive manner. This marks a groundbreaking turning point in Japan's defense posture and has the potential to significantly impact the security environment in Northeast Asia.

According to a statement released by Japan's Joint Staff Office this past Tuesday, the Self-Defense Forces will deploy multiple escort ships, aircraft, and the Type 88 Surface-to-Ship Missile system to the Philippines. During the exercise, comprehensive training will be conducted across air, land, sea, and cyberspace, including maritime strike operations, live-fire training for amphibious landings, and integrated air and missile defense. This scale represents the largest participation in overseas exercises for Japan to date, making it the third-largest contributor of military forces after the United States and the Philippines.

The strategic implications of this deployment are clearly focused on the potential for a crisis in Taiwan. The waters from the Taiwan Strait to the Bashi Channel and the South China Sea are directly linked to Japan's lifeline for energy transport and maritime traffic. Approximately 90 percent of Japan's crude oil imports pass through these waters from the Middle East, and if China were to implement a maritime blockade along the First Island Chain, the impact on the Japanese economy could be devastating. The deployment of the Type 88 anti-ship missiles is intended to build denial capabilities in these waters, making it critically important for securing intervention routes from the south of Taiwan.

On the other hand, China is also strengthening its countermeasures. According to an analysis in the latest issue of the Chinese military magazine "Shipborne Weapons," the People's Liberation Army (PLA) has revealed plans to blockade Japan's islands, including the southwestern islands, and the waters around the Philippines through "offensive mine laying" using the AJX002 drone. The article states that mine deployment around Taiwan's main island is unnecessary, while emphasizing the comprehensive blockade capabilities mobilized through land-based missiles, aircraft, submarines, and carrier strike groups. Notably, the PLA specifically mentions the potential for mine warfare against key maritime corridors, ports, and shipping routes along the First Island Chain to prevent supply to the "intervention forces" of the U.S. and Japan.

The AJX002 drone, according to publicly available information, is an underwater unmanned system capable of long-duration autonomous navigation, allowing for precise mine placement that was difficult with traditional mine warfare. Unlike operations conducted by conventional mine-laying vessels, deployment by drones is harder to detect and does not involve human risk. This technological advancement presents new challenges for the defense of Japan's southwestern islands along the First Island Chain. The Japan Maritime Self-Defense Force is currently modernizing its mine countermeasure vessels, but building countermeasures against decentralized mine laying by autonomous drones requires responses that go beyond traditional mine warfare tactics.

The United States also shares this threat perception. At a congressional hearing held this week, the Pentagon reiterated its vigilance regarding China's "invasion rehearsals," and the Trump administration requested the largest military budget in history. Particularly noteworthy is the diversification of China's military pressure on Taiwan, which now includes space operations, with threats in cyberspace, electronic warfare, and outer space being evaluated in an integrated manner alongside traditional maritime and aerial threats.

Japan's participation in the Balikatan exercise materializes the shift outlined in the national security strategy formulated in 2022. This strategy is centered on achieving "2 percent of GDP in defense spending" and acquiring "counterstrike capabilities (stand-off defense capabilities)," and the deployment of the Type 88 missile system can be seen as a practical implementation of the latter. However, Japan's legal constraints still exist. The exercise of collective self-defense is only permitted under limited conditions, and there is no mutual defense treaty between Japan and the Philippines like that between the U.S. and the Philippines. Discussions regarding whether the Self-Defense Forces' overseas deployment falls under "situations in the vicinity" or "situations that could have a significant impact," or "situations that threaten Japan's survival," including legal interpretations under domestic law, are expected to continue.

The situation in South Korea cannot be overlooked either. It has been analyzed that the "Goldilocks" missile developed by South Korea could threaten China's presence in the Middle Eastern arms market. In recent years, South Korea's defense industry has enhanced its international competitiveness in terms of quality and price, rewriting the map of defense equipment transfers in Northeast Asia.

The security situation in Northeast Asia in the spring of 2026 is unfolding in a more complex manner, characterized by the U.S.-China confrontation across the Taiwan Strait. The fact that Japan's Self-Defense Forces are participating proactively in the Balikatan exercise for the first time suggests that defense cooperation among Japan, the U.S., and the Philippines is becoming institutionalized beyond mere exercises. At the same time, China's mine warfare plans using the AJX002 drone indicate that the competition for maritime superiority along the First Island Chain has entered a new phase. Maritime security in Northeast Asia is transitioning from a traditional balance of power involving surface vessels and aircraft to a multidimensional competition that includes unmanned systems, missile defense, and cyberspace. The reconstruction of defense posture to respond to this shift has become the top priority in Japan's security policy.