Progress in Anti-Submarine Cooperation of the Maritime Self-Defense Force at Malabar 2026: The Realism of the Japan-U.S.-Australia-India Exercise

On November 5, the opening ceremony of Malabar 2026 was held at Yokosuka, featuring the Japan Maritime Self-Defense Force (JMSDF) destroyer "Ise." This exercise, which will continue in the southern Kanto sea area until November 12, involves four countries: Japan, the United States, Australia, and India. JMSDF destroyers and submarines, as well as the U.S. Navy's P-8A Poseidon patrol aircraft, will be deployed. The connectivity on the ground, including underwater operations, is what should be focused on, rather than the "Quad diplomacy" displayed on the screen.

Three-Dimensional Training Expanding from "Ise"

According to NHK's report on the JMSDF announcement, about 200 commanders and personnel participated in the opening ceremony. The U.S. Pacific Fleet announced that, in addition to the P-8A, it would dispatch the San Antonio-class dock landing ships "Anchorage" and "John P. Murtha." The training structure combines surface, submarine, air, and information domains, training in a continuous flow from detection, position assessment, tracking, to response.

Kyodo News reports that the exercise includes anti-submarine warfare and responses to surface forces. For the JMSDF, this is not merely a multilateral training involving port calls. Based on the stealth of submarines, it will be an opportunity to confirm how well the wide-area surveillance of the P-8A, the sonar of the destroyers, and the tactical data sharing among the vessels of various countries can be synchronized.

Improvement of Capabilities and Management of Intentions

Malabar began in 1992 as a small bilateral training between the U.S. and India, and the U.S. Seventh Fleet explains that 2026 marks its 30th anniversary, with all four countries participating for the sixth time. The Indian Navy operating with the U.S., Japan, and Australia in the Western Pacific is significant for considering the SLOC (Sea Lines of Communication) extending from the Indian Ocean through the Strait of Malacca to the South China Sea as a single operational environment. Choosing the Yokosuka area also sends a political signal of inviting distant partners into Japan's defense perimeter.

However, improving joint operational capabilities and having the same political will in times of crisis are separate issues. While India is aware of the competition with China, it is not an ally. If Japan interprets the results of the exercise directly as mutual defense in a crisis, excessive expectations could destabilize deterrence. Conversely, the more common tasks such as communication procedures, anti-submarine searches, resupply, and casualty evacuation are accumulated, the more room there is for cooperation while still holding different intentions among the countries.

Invisible Burdens Remaining for the JMSDF

The JMSDF's challenges are not limited to whether it can deploy vessels for the exercise. Continuing training that includes submarines and patrol aircraft requires skilled personnel, maintenance staff, interpreters and information officers, as well as long-duration data analysis capabilities. Compared to discussions about increasing the number of vessels, this human sustainability is less noticeable, but in anti-submarine warfare, a single communication delay or classification error can create gaps in vast maritime areas.

The true measure of evaluation is not the number of vessels lined up at the opening ceremony, but whether different navies can understand the same submarine contact in the same way and choose the next action within minutes.

Malabar 2026 demonstrates the unity of the Quad. However, according to Tanaka's assessment, the most cautious risk to consider is not the reaction from China, but rather that the participating countries might confuse the interoperability achieved in the exercise with the strength of a political alliance.

Reference Information

• NHK WORLD-JAPAN (November 5, 2026) https://www3.nhk.or.jp/nhkworld/news/20261105de71272/
• Kyodo News (November 5, 2026) https://english.kyodonews.net/articles/-/90476
• U.S. Pacific Fleet (November 5, 2026) https://www.cpf.navy.mil/Newsroom/News/Article/4642982/funakoshi-hosts-forces-from-australia-india-japan-and-us-for-start-of-exercise/
• USNI News (October 29, 2026) https://news.usni.org/2026/10/29/u-s-partner-nations-to-hold-annual-malabar-naval-exercise-near-japan