A Strategic Nexus for Japan

Southeast Asia offers new opportunities for maritime security partnerships

Cmdr. (Ret.) John F. Bradford/U.S. Navy

Japan’s maritime strategy is fundamentally focused on partnering with its ally the United States to ensure that the Indo-Pacific sea lanes critical to its security are safe and secure. Most of the activities by its two maritime security services, the Japan Maritime Self-Defense Force (JMSDF) and Japan Coast Guard (JCG), are focused on Japan’s near seas and seek to deter aggressive actions by the People’s Republic of China (PRC), North Korea and Russia while enabling good governance of the Japanese exclusive economic zone. Japan also deploys its forces to locations along those sea lanes, such as the Gulf of Aden and Strait of Hormuz, where Japanese shipping is under significant and direct threat. Equally critical to the strategy are the Japanese activities aimed at the relatively more safe and secure, yet still vulnerable sea lanes that pass through and near Southeast Asia. This includes enclosed seas, such as the South China Sea, Java Sea and Bay of Bengal, as well as critical chokepoints, such as the Lombok, Malacca, Singapore and Sunda straits.

Much of this effort draws on Japan’s economic strength, and Japan has been heavily invested in developing infrastructure and safety capacity alongside the region’s coastal states for more than 50 years. For the past 20 years, the JCG has also been engaged with developing the coastal states’ maritime law enforcement capacity. In the past decade, the Japanese Ministry of Defense has become involved by starting new capacity-building projects with regional navies, and the JMSDF has been increasingly conducting military operations in the regional waters.

With all branches of Japan state power now investing in Southeast Asian maritime security, this region is cementing itself as a new nexus in Japan’s maritime strategy. The scope, strategic intent and likely future development of Japan’s maritime security activities in Southeast Asia merit closer examination.


Japan’s well-established maritime security strategy can be broadly separated into two geographic segments, one pertaining to Japan’s home waters and the other to Indo-Pacific sea lanes. In its near seas, Japan faces significant security pressures from the north, west and south. Aggressive contemporary military postures, territorial disputes and war legacy issues create security concerns and constrain cooperation between Japan and its neighbors Russia, the PRC and the Koreas.

In the maritime space, the competition with the PRC is the most strained. The concentric rings of Japanese and PRC coast guards and naval forces persistently contest sovereignty, probe reactions and seek to assert control over the waters surrounding the Senkaku Islands. This situation demands significant fleet resources while the remainder of the East China Sea provides a long front for patrol and surveillance. The ballistic missile threat from North Korea and Japan’s support for the enforcement of United Nations Security Council sanctions against that state also keep the fleet busy. Above the waters approaching Japan, the Japan Air Self-Defense Force regularly scrambles fighters in response to PRC and Russian flight operations. Given this increasingly severe situation, protecting Japan’s rights and executing its national responsibilities in the sea and airspace under the U.N. Convention on the Law of the Sea have occupied the bulk of Japan’s security resources.  

Japan’s strategy to ensure the safety and security of its critical sea lanes rests on three elements: leveraging its alliance with the U.S., deploying forces to most critical threat locations and strengthening relations with increasingly capable partners along the sea routes.

Vietnam Coast Guard officers watch a helicopter depart from the Japan Coast Guard ship Echigo during combined training off Vietnam’s coast near Danang. AFP/GETTY IMAGES

In recent years, Japanese maritime strategy has nested under national campaigns to focus Japan’s foreign policy in the Indo-Pacific band that stretches along its sea lanes to Europe and Africa. Shortly after former Prime Minister Shinzo Abe assumed office for the first time in 2006, then-Foreign Minister Taro Aso announced the Arc of Freedom and Prosperity. This foreign policy complemented Japan’s existing priorities involving managing relations with immediate neighbors and strengthening the U.S. alliance, with an additional emphasis on promoting democracy and increased capability with an arc of partner nations stretching from Northern Europe, through the Middle East, past the Indian subcontinent and across Southeast Asia. Notably, this arc aligned geographically with Japan’s main trade routes, minus those across the Pacific Ocean that were already secure, thanks to the U.S. alliance. Abe became the first global leader to highlight the Indo-Pacific geopolitical concept when he gave a 2007 address to the Indian Parliament titled “Confluence of the Two Seas.” The next two prime ministers, both from the Liberal Democratic Party, continued with this prioritization. When the Democratic Party of Japan led the government from 2009-12, Prime Ministers Yukio Hatoyama, Naoto Kan and Yoshihiko Noda used different branding but sustained this foreign policy approach toward the coastal states of South and Southeast Asia. Immediately after returning to power in 2012, Abe published an essay titled “Asia’s Democratic Security Diamond.” It opened with: “Peace, stability and freedom of navigation in the Pacific Ocean are inseparable from peace, stability and freedom of navigation in the Indian Ocean. Japan, as one of the oldest sea-faring democracies in Asia, should play a greater role — alongside Australia, India and the U.S. — in preserving the common good in both regions.”

Southeast Asia was clearly at the heart of the diamond, and it is now the nexus of the Free and Open Indo-Pacific vision announced in 2016.


The sea lanes between Japan’s home waters and the dangerous sea space around the Middle East stretch for more than 5,000 nautical miles (9,260 kilometers). For the most part, these sea lanes pass by coastal states capable of providing the governance needed to ensure safety for the free flow of commerce. However, the coastal states vary widely in terms of maritime capacity, the sea lanes are far from hazard-free, and Japanese business and government leaders worry that disruptive events could quickly create a crisis. The hazards that concern Japan include the navigation challenges associated with heavily traveled chokepoints, environmental challenges, such as extreme weather and oil spills, piracy, terrorism and war risks. For the past five decades, Japan has become increasingly involved in addressing these challenges by supporting coastal state capacity-building projects as a core element of its maritime security strategy.

The rise of regional piracy rates in the wake of the 1997 Asian monetary crisis catalyzed an expansion of Japan’s capacity-building efforts to include maritime law enforcement. Prime Minister Keizo Obuchi kick-started this expansion at the Association of Southeast Asian Nations Plus Three (ASEAN+3) summit in December 1999, when he sought international cooperative action against piracy by proposing the establishment of a regional coast guard body, the strengthening of state support for shipping companies and improvement of regional coordination. 

Soon, Japan was offering equipment and training and pressing for combined patrols. After a series of Japanese fact-finding delegations visited the region and Tokyo hosted several large conferences, Japan’s ambitions were scaled back, but the expanded involvement in Southeast Asian maritime law enforcement nonetheless came quickly. In 2000, the JCG began establishing permanent overseas positions for officers to support regional coast guards (starting with the nascent Philippine Coast Guard), and in 2001, the JCG began exercising with regional coast guards (starting with the Philippines and Thailand). In 2006, Japanese diplomatic efforts culminated in the creation of the Regional Cooperation Agreement on Combating Piracy and Armed Robbery against Ships in Asia (ReCAAP).

People wave as the Japan Maritime Self-Defense Force destroyer JS Takanami leaves Yokosuka Naval Base in Japan. AFP/GETTY IMAGES

A notable aspect of Japan’s support for Southeast Asia’s maritime security has been the transfer of patrol boats to regional maritime law enforcement agencies. These have included converted fishing vessels, retired Japanese patrol boats and new vessels. They have been provided by private Japanese foundations, through government-facilitated loans, and as direct assistance. Early examples are the transfers to Indonesia and the Philippines in the mid-2000s. As these vessels were armored, the transfers were governed by Japan’s Three Principles on Arms Exports and the receiving partners could only use them for law enforcement operations, to include anti-piracy and counterterrorism. Relaxation of the Three Principles in 2011 and 2014 has streamlined the policy process, and in recent years, Japan has expanded its programs to provide patrol vessels. To date, coast guard and maritime law enforcement agencies in Cambodia, Indonesia, Malaysia, Palau, the Philippines, Sri Lanka and Vietnam have received patrol vessels from Japan.


The earliest JMSDF ship deployments aimed specifically at impacting the Southeast Asian maritime security situation aligned with multilateral efforts and frameworks. In December 2004, Japan Self-Defense Forces (JSDF) ships and aircraft were among the international forces that responded to the Indian Ocean tsunami. In 2005, the JMSDF participated in the inaugural Western Pacific Naval Symposium (WPNS) at-sea exercise hosted by the Republic of Singapore Navy, and Japan Ground Self-Defense Force officers participated in the tsunami relief workshop and high-level staff portions of the Thai-U.S. military exercise Cobra Gold. Since then, maritime exercises sponsored by multilateral organizations such as WPNS, the ASEAN Regional Forum and the ASEAN Defence Ministers Meeting-Plus (ADMM+) have become more frequent, and the JMSDF has consistently participated, often sending the largest contingents. While significant from a defense diplomacy perspective, these multinational maritime exercises were often quite simple and aimed more at confidence-building than strengthening operational capacity. Many of them focused on disaster response rather than more traditional security concerns.

Japan’s National Defense Program Guidelines of 2010 became the first major policy to state that the JSDF would begin conducting capacity-building missions with foreign militaries. The first operation under this policy was the 2010 deployment of a JMSDF ship to conduct capacity-building activities in Cambodia and Vietnam as part of the U.S. Pacific Partnership campaign. Since then, JMSDF ships have participated in Pacific Partnership annually, only missing 2011 when they were supporting domestic disaster-response operations in the wake of an earthquake and tsunami. In 2012, Japan executed its first bilateral capacity-building activity in Southeast Asia, an underwater medicine seminar held with the Vietnam Navy. The second bilateral event was a February 2013 oceanography-focused seminar at the Indonesian Navy Maritime Operations Center in Jakarta. Since then, Japan has conducted similar bilateral capacity-building activities with eight other partner nations. Of these 10 partners, all but Mongolia are South China Sea or Bay of Bengal coastal states. 

In December 2013, Japan’s first National Security Strategy explained the strategic intent behind these activities: “Japan will provide assistance to those coastal states alongside the sea lanes of communication and other states in enhancing their maritime law enforcement capabilities and strengthen cooperation with partners on the sea lanes who share strategic interests with Japan.” 

In the past decade, the JMSDF has also expanded operations in the South China Sea. Unlike the multilateral exercises and capacity-building activities previously mentioned, these activities appear to be more focused on developing options to conduct high-end naval operations around that body of water. Since Japan does not publicize the locations of its ships and submarines, it is unclear when these deployments began. 

Some analysts, including retired Japanese admirals, argue that the JMSDF is also readying to counter a potential PRC ballistic missile submarine bastion in the South China Sea. Such a concern would help explain the JMSDF’s emphasis on its partnerships with the Philippines and Vietnam, the nations that straddle the sea’s northern section and flank the important PRC submarine base on Hainan island.

The JMSDF’s relationship with the Philippine Navy is the most developed of its Southeast Asia partnerships. JMSDF officers began observing the annual Philippines-U.S. Balikatan exercise in 2012 and involvement later increased. In 2016, Japan’s training submarine Oyashio visited Subic Bay in the Philippines alongside two JMSDF destroyers, and the crews took part in confidence-building activities with Philippine counterparts. This was the first JMSDF submarine port call to the Philippines in 15 years. Since then,
JMSDF submarines have been frequent visitors to
Subic Bay.

The Philippines is also the first and, thus far, only nation to acquire Japanese defense equipment. Policy reforms in 2014 allowed Tokyo to approve defense exports to partner militaries, and in 2017, two used JMSDF TC-90 training aircraft were delivered to the Armed Forces of the Philippines, where they were designated as C-90 maritime patrol aircraft. Three additional TC-90s were transferred in 2018. 

Japan has also prioritized development of its defense relations with Vietnam. The first JMSDF capacity-building activity in the region was during the 2010 dispatch of the amphibious transport dock ship
JS Kunisaki to Qui Nhon, Vietnam, under the Pacific Partnership umbrella. While focused on medical treatment activities and cultural exchanges, the visit included the use of amphibious vehicles landing on a Vietnamese beach. The next year, Vietnam hosted the first JSDF capacity-building activities in Southeast Asia not facilitated as part of a U.S. or multilateral event. Since then, the relationship has grown, though it has not yet reached a level that includes bilateral defense exercises or operations. 

Annual deployments of large helicopter carriers, such as the JS Izumo for a multimonth deployment to Southeast Asia and the Indian Ocean, encapsulate the varied nature of JMSDF activities in the region. In 2016, during the first of these deployments, the JS Ise was the largest ship at the multinational exercise Komodo hosted by Indonesia. The ship then transited to the South China Sea with a cadre of midshipmen from WPNS navies for training while conducting a trilateral passing exercise with Royal Australian Navy and U.S. Navy ships. After a goodwill visit to Manila, the JS Ise was the largest ship involved in the May 2016 ADMM+ Maritime Security/Counter-Terrorism Field Training Exercise that began in Brunei and concluded in Singapore. The following year, the JS Izumo, the JMSDF’s largest ship, made a similar deployment to Southeast Asia that included: a maritime security training program for officers from ASEAN navies while the ships were in the South China Sea; hosting Philippine President Rodrigo Duterte during a port visit to Manila; calling in Sri Lanka; and completing two days of exercises with ships from Australia, Canada and the U.S. that included cross-deck exchanges and live-fire events. Similar deployments in 2018 (JS Kaga) and 2019 (JS Izumo) blended unilateral operations in the South China Sea, exercises with the U.S. and other navies, support for multilateral maritime security programs and bilateral relationship-building with regional partners.


The blended nature of the JMSDF capital ship deployments to Southeast Asian waters reflects its multifaceted maritime goals in the region. Japan is expanding on decades of capacity-building initiatives in the region to include military dimensions. These activities are aimed at strengthening relationships with increasingly capable coastal states along Japan’s Indo-Pacific sea lanes. These naval activities are, in some ways, a simple progression of Japan’s long-standing policy to support maritime capacity development. However, this expansion reflects a loosening of Japan’s domestic policy constraints and the increased comfort of Southeast Asian partners in hosting Japanese forces. The PRC’s increasing capabilities and assertive maritime behavior have hastened this trajectory, given Japan’s heavy reliance on the South China Sea and its concerns that the PRC’s campaign to assert sovereignty there is strongly linked to its campaign against Japan in the East China Sea.

Japan’s overarching strategic goal to promote the sustained safety and security of the critical Southeast Asian sea lanes has remained essentially unchanged for more than 50 years. However, Japan has incrementally expanded the range of regional security challenges it directly addresses and the agencies it mobilizes to assist in this effort. For the past decade or so, these agencies have included the Ministry of Defense and the JMSDF. The JMSDF now regularly deploys to the South China Sea and has a record of conducting high-end warfare exercises with the U.S. and other extra-regional navies in that contested body of water. It makes major contributions to multilateral exercises in the region and has been conducting bilateral capacity-building activities with regional navies. The activities should be expected to continue to expand with the primary limiting factors being the availability of ships and other fleet resources.

To date, the bilateral engagements in Southeast Asia have been almost entirely restricted to goodwill activities and modest projects focused on building regional partners’ constabulary capacities. However, Japan can be expected to become more involved in assisting regional states with military defense capabilities. The deal to send new air defense radars to the Philippines sets a precedent in this regard. The PRC’s continued maritime aggression will be an important driver, but Japan will remain concerned by other maritime threats and increasingly seek to diversify its defense relations beyond reliance on the U.S.

With the Ministry of Defense and JMSDF joining other Japanese agencies as direct participants in Southeast Asian maritime security, the region has clearly become a new nexus in Japan’s maritime strategy. It is important for Southeast Asian states to realize that as Japan’s self-restraint relaxes, they will face bigger decisions regarding the nature and scope of the defense relations they desire with Japan.  

The Center for International Maritime Security originally published this article in September 2020. It has been edited to fit FORUM’s format.

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