The Case for Japanese Land Power in the First Island Chain
Vladimir Lenin reputedly said, “There are decades where nothing happens; and there are weeks where decades happen.” The year of 2022 was exactly this kind of period, when years of developments were compressed: Lenin’s descendants ironically launched an unprovoked and unlawful war against Ukraine; the Taiwan Strait witnessed a once-in-a-decade crisis after U.S. House Speaker Pelosi’s visit to Taiwan; and North Korea set a record for conducting more than 70 rounds of missile tests in just one year.
It is no wonder that Japan’s three strategic documents, released at the end of 2022, are marked by an uncharacteristically anxious tone. These documents are Japan’s response to the deteriorating regional and global security situations. Two of those documents — Japan’s National Defense Strategy and the Defense Buildup Program — set targets for future capabilities and posture of the Japan Self-Defense Forces to address the emerging security outlook. Scrutinizing the two documents reveals that the Japan Self-Defense Forces’ land component, the Ground Self-Defense Force, is the service which will undergo the most significant transformation in the coming decade compared to the rest of the Japanese military.
In light of the operational problems the Japan Self-Defense Forces and the U.S. military need to address, a new Ground Self-Defense Force could play a key role in enabling not only Japan’s own joint operations but also bilateral operations with the U.S. military along the first island chain. While maritime and air forces are susceptible to the threat of long-range strikes, ground forces can keep operating in areas within range of adversaries longer-range missiles and take advantage of land-based infrastructure to protect the Japanese littoral and, potentially, to work with the United States. The role of Japan’s ground forces is critical for the future of the country and the Japan-U.S. alliance but is often overlooked in favor of the country’s air and maritime forces. This re-discovered significance of Japanese ground forces presents a set of challenges for the Japanese and U.S. militaries to tackle together to respond to contingencies. One of such challenges is to fully integrate both militaries in order to synchronize their situational awareness and amplify the lethal and non-lethal effects they bring to bear.
Japanese Understanding of the Strategic Environment
The Japanese people regard Russia’s aggression against Ukraine as an egregious example of an authoritarian state invading another sovereign state. In terms of international norms, if left unchecked, Russia would demonstrate to other revisionist states the ease of changing the status quo by force, encouraging them to do the same. On a global scale, the war in Ukraine is the most violent manifestation of accelerating confrontation between the free world and the authoritarian states. Japan has also witnessed closer alignment between the Russian and Chinese militaries around the Japanese islands, including joint aerial patrols and maritime exercises. Therefore, the war in Ukraine is not simply a local conflict far away from home for Japan but rather a fateful occurrence that evokes a sense of crisis among ordinary Japanese citizens.
The fault line between the free world and the authoritarian one runs through the west of the first island chain — the Japanese archipelago that interlocks with Taiwan and then down to the Philippines. Japan finds itself on the frontline of free nations at the very moment of heightened confrontation between the United States and China, especially over the fate of Taiwan. Because of its unique geopolitical position, Japan is now a pacing ally for the United States while China has emerged as its pacing challenge. The perimeter Japan holds is critical not only for itself but also to like-minded countries in the Indo-Pacific.
In response to this new geopolitical environment, Japan’s new security strategies clearly acknowledge China as the “unprecedented and greatest challenge” to its security. This is a first in the country’s post-World War II history. Beijing has never renounced the option of using violent force to annex Taiwan and has grown more aggressive in both maritime and air domains along the first island chain. The fact that China fired missiles into Japan’s exclusive economic zone after Speaker Pelosi’s recent visit to Taiwan inadvertently demonstrated that Japan and Taiwan geographically belong to the same sub-theater — the distance between Taiwan’s east coast and Japan’s westernmost island of Yonaguni is only 111 km. North Korea, too, continues to threaten Japan with its hundreds of ballistic missiles. Surviving saturation attacks of their ballistic and cruise missiles would be a daunting challenge for Japan.
Japan’s Future Land Power
While Japan’s new National Security Strategy sets principles for a whole-of-government effort to meet regional and global security challenges, the National Defense Strategy, of which previous versions were called the National Defense Program Guidelines, specifically discusses how Japan’s military instruments will be employed to achieve security objectives. It simultaneously explains the future capabilities and posture the Japan Self-Defense Forces will develop over the next 10 years. Public attention has focused on the announcement to double defense spending in five years and the decision to introduce so-called counterstrike capabilities.
As important as these announcements are, the issues are only part of a larger whole: a strategy of denial. The government believes that the Japan Self-Defense Forces should possess sufficient capabilities and capacity to deny any potential adversaries from invading Japan. The level of capabilities and capacity to do this needs to be based on the capabilities of potential adversaries and also take into account recent developments about the characteristics of warfare. For example, the war in Ukraine has witnessed large-scale attacks by ballistic and cruise missiles; information operations integrated in hybrid warfare; asymmetric attacks in the space, cyber, and the electronic domains; and wide use of unmanned platforms.
As the land component of the Japanese joint force, the Ground Self-Defense Force is expected to understand the new reality and then optimize its architecture to best support joint and bilateral operations with the United States. Based on gaps identified in its current capabilities and capacity, the Ground Staff Office has established four lines of efforts for its transformational modernization. First, the ground service will continue to strengthen cross-domain operation capabilities across the land, sea, air, space, cyber, and electromagnetic domains. It will increase its cyber-electromagnetic activities capabilities and create new electronic warfare units especially along the Ryukyu Islands. The cognitive domain is also defined as critical, where artificial intelligence will be introduced to achieve dominance in decision-making. This effort will include investing more in land-based air defense systems as a part of the Japanese integrated air and missile defense network and increase the number of anti-air artillery from the current seven groups to eight.
Second, Japan’s stand-off missile arsenal will be dramatically scaled up. The Ground Self-Defense Force will expand its surface-to-ship missile artillery from five regiments to seven, equipping them with an updated version of the Type-12 anti-ship missile with extended range. It will also create two new battalions that will field high-velocity gliding projectiles as well as two other units armed with hypersonic cruise missiles.
The Ground Self-Defense Force will also field a fleet of new drones in order to strengthen its own kill chain with Japanese intelligence, surveillance, reconnaissance, and targeting functions. All these would mean significantly expanding and deepening Japan’s ability to strike targets along the first island chain, which will make the area “contested environment” for potential adversaries.
Third, the Ground Self-Defense Force will be quicker and faster to deploy and move along critical terrain on the East China Sea. The ground service will enhance its mobility by supporting the creation of a new joint watercraft unit equipped with logistics support vessels and landing craft utilities, which will be launched by the end of 2024 as the Maritime Transportation Group to transport ground troops. The transportation requirement will also be reduced by creating a new depot in Okinawa to increase prepositioned supplies together with the joint or shared use of the U.S. military’s Kadena Ammunition Storage Area. In addition, the 15th Brigade — the only tactical formation in Okinawa — will be upgraded into a division as the pre-deployed unit in the area.
Finally, this transformation will make the Ground Self-Defense Force more sustainable and resilient. All divisions and brigades, with the exception of the 15th Brigade, will be restructured to become more deployable with smaller, self-sufficient packaged regiments. These units will soon have their own intelligence, fires, air defense, and logistics dispersed in wide areas to survive, fighting independently under the threat of the enemy’s long-range precision strikes.
The Case for Japanese Land Power in the First Island Chain
The region’s geography shows the criticality of ground forces. From an operational perspective, Japan is a key maritime terrain in the western Pacific. The force that controls this littoral has the ability to significantly influence events seaward. Potential adversaries are acutely aware of its value, viewing Japan as a fortified barrier obstructing access to the ocean. Ceding any part of this terrain to adversaries would jeopardize the Japanese military’s entire operations while also forfeiting the most precious advantage for allied forces along the first island chain as well. Americans did not have to worry about the control of this archipelagic terrain in the past. During the Korean War in the 1950s, Japan served as a secure rear base for U.N. forces operating on the Korean Peninsula. At the time, neither China nor North Korea had the means to strike these areas. This is not the case anymore, as the entirety of Japanese territory falls within range of all of the regional adversaries’ long-range strike capabilities.
The role of the Ground Self-Defense Force is to seize and retain key terrain. Maritime and air forces are employed in a more dynamic way, sometimes maneuvering forward to deliver strikes, sometimes disengaging rearward to minimize risks to platforms. Potential adversaries have reportedly targeted Japanese air bases and naval bases and are regularly rehearsing strike operations. Being vulnerable to initial volleys of missile strikes, maritime and air forces have every reason to save their combat power for decisive engagements in the later phases of combat. In contrast, the complex archipelagic terrain itself provides ground forces with specific means for cover and concealment and sufficient maneuver space to disperse and survive. While this holds true for any ground forces operating on the first island chain, the Ground Self-Defense Force has certain advantages because of its unhindered access to existing garrisons, depots, logistic facilities, and other infrastructure spread across the nation. Over the past decade, it has created new garrisons on the Ryukyu Islands, just north of Taiwan, with the last one on Ishigaki Island scheduled to be launched in March 2023. All of these could support joint and bilateral operations in an East China Sea contingency.
Japanese Ground Forces Contribution to Joint and Bilateral Operations
Holding maritime terrain will not be an easy task. Having learned painful lessons in the closing days of the Pacific War, the Japanese military is acutely aware of the difficulty — and costs — of defending islands when faced with enemy superiority in the air and on the sea. Today, all domains — not only maritime and air domains — are contested due to technological advances in sensing, ranges, and lethality. Japanese ground forces will need to fight just to stay in the conflict. By doing so, however, the Ground Self-Defense Force can be key enablers for joint operations, especially for those bilaterally conducted with the U.S. joint force.
The “tyranny of distance” in the Indo-Pacific has become a military cliché but remains a reality. The problem will be more acute with relative growth in potential adversaries’ capabilities. Gaps in time and distance are fundamental challenges for the U.S. military projecting power in the western Pacific. The U.S. joint force will have to fight first to get to the fight, whereas the Ground Self-Defense Force will need to fight to stay in the fight. Adversaries will employ every means to widen and exploit such gaps to keep the U.S. joint force at arm’s length. They will likely seek to influence the minds of American decision-makers with perceived costs in order to deter them from intervening. The worst scenario for America’s allies — and the most desirable one for their adversaries — is that the adversaries establish a fait accompli along the first island chain long before the U.S. military can mount any armed response.
With these challenges in mind, Ground Self-Defense Force units are tasked to operate in situations below the threshold of conflict and in kinetic operations. During competition below the threshold of violence, the forces are designed to maintain a presence on the Ryukyu Islands. The presence of their long-range strike capabilities would especially complicate adversaries’ calculus and planning, providing a shield for interagency partners directly confronting adversaries on the sea. The Japanese military should learn from the playbooks of adversaries who deploy land-based missiles to support coercive behaviors of their maritime law enforcement organs. Ground Self-Defense Force units constantly monitor and track adversaries’ activities in the theater, dynamically deploy and rotate troops along the first island chain, and send signals through training and exercises, all aimed at deterring potential adversaries from changing the status quo. Those activities could be conducted as a part of joint, bilateral, and even multilateral operations. They will serve the purpose of preparing for conflict — to include persistent target development — as well as that of deterring adversaries. This would help bridge the temporal gap so critical to the U.S. joint force.
If deterrence fails and hostilities commence, Ground Self-Defense Force units in the area operate as stand-in forces, well within range of enemy missiles. They can persist in position even without the immediate presence of sister-service forces. Reinforced by additional ground forces deployed from elsewhere, Japanese stand-in forces firmly retain key maritime terrain, maintaining the forward edge of the contact line. Such forces gain and maintain custody of the enemy targets with their own sensors, supporting joint surveillance and reconnaissance to assist the Japanese joint force delivering strikes. If directed, they can conduct sea- and air-denial operations with their long-range strike and air defense capabilities together with other joint assets available then. The Ground Self-Defense Force simultaneously protects land-based foundational capabilities across the nation, not only for itself but also for sister services and U.S. forces stationed in Japan. It is by gaining friendly situational awareness, maintaining positional advantage, denying the enemy freedom of movement, degrading the enemy combat power, and opening corridors for friendly maneuver that such Japanese stand-in forces would set conditions for introducing the Japanese and U.S. joint forces to areas of their decisive engagements. Drawing from an analogy of land operations, Japanese ground forces in the forward edge would operate as a covering force for the main body of bilateral joint forces: They would allow the main body of the stand-off forces to maximize their destruction potentials as well as minimizing risks to their platforms. With their posture established in a steady state, Ground Self-Defense Force units would raise prospective costs for adversaries to launch military actions while significantly reducing those for the U.S. joint force to intervene along the first island chain. This would compel adversaries to give up their malign intentions in the western Pacific from the start.
Opportunities offered by a refashioned Ground Self-Defense Force will inevitably entail a range of challenges for Japan and the United States. First and foremost, the roles of ground forces on the first island chain should be incorporated into the Japan-U.S. dialogue on the roles, missions, and capabilities at the policy level. Then, a couple of issues need to be addressed at the joint level: If Japanese stand-in forces shape conditions for the introduction of bilateral joint forces along the first island chain, both the Japan Self-Defense Forces and the U.S. military must first clearly articulate a shared purpose of the entire bilateral campaign — to include the defense of Japan itself and other contingencies — based on a clear theory of victory. Such a shared purpose should be informed by policies on both ends — not only because political objectives drive purposes of military campaigns, but also because such planning efforts may require optimizing the capabilities and posture of both Japanese and U.S. forces in the theater, which could be politically sensitive. A shared purpose would enable unity of bilateral efforts: The Japan Self-Defense Forces and U.S. military could integrate their operations across phases and warfighting functions through detailed planning and day-to-day coordination.
Among a range of functions, especially keen is the need to integrate command, control, communications, computers, intelligence, surveillance, and reconnaissance. Looking back to examples in military history, lack or disruption of communication between a covering force and the main body is a recipe for disaster — especially that of being destroyed in detail. This is not simply the same old story of sharing more information and becoming more interoperable. Rather, Japanese and U.S. forces should fully integrate their situational awareness, sharing data itself. They should design an architecture to allow for such integration which would be compatible with their respective policies and regulations, supported by robust information security measures.
Furthermore, the Japan Self-Defense Forces and the U.S. military should be prepared to build “bilateral kill webs,” supported by AI-enabled networks, into which all the sensors and shooters of both forces could be plugged in together, matching them automatically at the speed of light. Given the relative combat power in the area weighing against the Japanese and U.S. militaries, and with no prospect of achieving dominance again over their adversaries, they must not spare any effort to forcibly create windows of opportunity. Both militaries should see the value, for example, of Ground Self-Defense Force Type-12 anti-ship missiles sinking enemy vessels spotted by a U.S. Marine Corps F-35B or U.S. Army hypersonic missiles striking targets identified by Ground Self-Defense Force electronic warfare sensors.
At the service level, the Ground Self-Defense Force must synchronize its institutional efforts with those of its U.S. counterparts — in particular, the U.S. Army and Marine Corps. The U.S. Army recently formulated multi-domain operations as its doctrine. Accordingly, the Army’s multi-domain task force might be employed as a key component to the contact layer along the first island chain. The U.S. Marine Corps, for its part, has tested concepts for expeditionary advanced base operations and stand-in forces, while transforming its architecture based on Force Design 2030. Already, the 12th Marine Regiment in Okinawa is being transformed into a Marine littoral regiment specially designed to conduct expeditionary advanced base operations. Both the U.S. Army and Marine Corps have struggled to adapt to the current operational environment. If all those units conduct similar missions with Ground Self-Defense Force units along the first island chain, their concepts and doctrines need to be logically aligned. Synchronizing ideas should involve more than occasionally doing targeting together in episodic training and exercises: It should go deeper into the philosophical level, leading to synchronization of theories of victory. This would then inform the best solutions regarding how to share responsibilities and support each other in various situations. For example, Ground Self-Defense Force command nodes and (forward) elements of U.S. ground forces may better integrate their targeting cycles, to include their persistent target development activities in a steady state. The intellectual undertaking should also lead, and be supported by, combined efforts to develop materiel that would allow for more integration. In particular, this should enable Japanese and U.S. systems to generate, manage, share, and use data in this era of data centricity.
In mid-January, Japan and the United States held talks between foreign and defense chiefs and confirmed that their respective strategies are closely aligned, share visions, priorities, and goal. The alliance between the two countries has never been stronger, with Japan being the pacing ally for the United States. This unprecedented alignment, however, is just a testament to the severity and enormity of the challenge the allies face. With storm clouds gathering, there is no time for complacency. At this juncture, Japan’s new strategies envision a refashioned Ground Self-Defense Force which will be more cross-domain, lethal, mobile, and survivable. As such, it will better support joint and bilateral operations with the U.S. military along the first island chain. Given its evolving roles and missions, the Ground Self-Defense Force has the opportunity to take the lead in the endeavor to modernize the alliance.
Col. Yusuke Kawachi is an artillery officer in the Japan Ground Self-Defense Force with command experience of a surface-to-ship missile battery. He currently serves as the military attaché at the Embassy of Japan in Washington, D.C. He received his undergraduate education at the University of Tokyo and holds master’s degrees from the University of Tokyo, the United States Marine Corps University, and the National Graduate Institute for Policy Studies. The views expressed are those of the author and do not reflect the official policy of the Japan Ground Self-Defense Force, the Japan Ministry of Defense, or the government of Japan.