A Time to Act: Japanese Security Between the United States and China
Introduction
The United States has taken action and increased pressure on European allies indicating a limited tolerance for perceived insufficient contributions to collective security efforts. Japan has also been the recipient of criticism for insufficient collective security contributions in a region the United States is keenly paying attention to… the Indo-Pacific. Japan remains susceptible to shifts in US attitudes and expectations regarding burden-sharing on defense, as well as more fundamental geopolitical shifts that will require Japan to fundamentally rethink its approach to defense. Japan must not become complacent. The United States recently upgraded its force structure in Japan by installing a Joint Force Command, but it can easily downgrade its force structure and shift resources to address other security priorities in the future. This necessitates a critical reassessment of Japan’s long-standing reliance on US support and underscores the need for Japan to take greater ownership of its own defense.
Evolving regional challenges increasingly reveal the inadequacy of Japan’s current security posture. Japan’s limited capacity for independent defense and power projection leaves it ill-equipped to protect vital regional interests, including the security of Taiwan and sea lines of communication. Addressing this gap in the coming years requires Japan to not only increase its defense commitments and make bold strategic adjustments but also to contend with domestic pressures like a chronically low birthrate and declining economic growth. These internal vulnerabilities are compounded by the primary external threats of a growing and increasingly aggressive Chinese People’s Liberation Army (PLA) and the uncertainty surrounding future US defense commitments to Japan. To fully grasp the imperative for Japan to act, the subsequent sections of this analysis delve into Japan’s anxieties concerning China’s military advancements and the Taiwan issue, followed by an examination of the evolving expectations from the United States that are compelling Japan to adapt its security posture. This article will then conclude by offering concrete recommendations for Japan to navigate this complex geopolitical landscape to strengthen its national security position.
Japan’s Deepening Concerns about China’s Military and Taiwan
China’s rapid military modernization and increasingly assertive behavior have long posed a challenge to Japan’s security, but this issue is now taking on a new sense of urgency. The People’s Republic of China (PRC) has been significantly increasing its defense spending and rapidly expanding its military capabilities with a critical lack of transparency. This military buildup is coupled with the PRC’s assertive actions in the East and South China Seas. The PRC actively intrudes into Japan’s territorial waters around the Senkaku Islands using both its conventional forces (Air Force and Navy) and gray zone assets (Coast Guard and maritime militia). The PLA’s military actions in the Sea of Japan threaten to reach the Pacific Ocean, which would effectively encircle Japan, similar to the PLA strategy around Taiwan. This demonstrates the PRC’s growing regional ambitions and the direct implications for Japan’s security.
Chinese Activities in the East China Sea, The International Military Environment on 2025 January Japan Ministry of Defense
This chart depicts Chinese military activities in the region and includes information on the type of vessel and aircraft, date of activity, type of activity, and location. This chart concludes that Chinese military vessels are constantly operating in the waters close to the Senkaku Islands and that Chinese military aircraft are also active in the airspace around the Nansei Islands, Senkaku Islands, and Okinawa.
A key factor elevating the urgency of this challenge is the growing convergence of Japan’s security concerns with the situation around Taiwan. While Japan has traditionally acknowledged the PRC’s position on Taiwan and follows a One China Policy, like the United States, it also recognizes Taiwan as an important partner with shared values and close economic ties. The PRC’s increasing military activities near Taiwan, including unannounced live-fire military drills, gray zone warfare, and Xi Jinping’s refusal to rule out the use of force, are seen by Japan as a rapidly growing concern. There is a recognition that a conflict in the Taiwan Strait will have a direct and severe impact on Japan’s security.
Japan’s vulnerability to a conflict over Taiwan is underscored by several critical factors. Its geographic proximity to Taiwan and heavy reliance on the sea lines of communication traversing the Taiwan Strait means that any conflict in the region would disrupt trade vital to Japan. A Taiwan conflict will disrupt Japan’s access to energy supplies, food imports, and outbound trade. Beyond these immediate concerns, Japan increasingly views Taiwan’s security as intrinsically linked to its own, recognizing that a Chinese takeover of Taiwan would significantly alter the regional balance of power. If the PRC is able to successfully takeover Taiwan, it will enable the PRC to project power further into the Pacific, threatening Japan’s Ryukyu Island Chain, and potentially leading to Japan’s isolation. Taiwan’s role as a key component of the First Island Chain further amplifies this risk. Control by the PRC would weaken the Indo-Pacific’s security architecture, reduce deterrence against Chinese expansionism, and potentially trigger a domino effect of destabilization in the region.
The growing threat posed by PLA military modernization and the potential for Japan to be drawn into a conflict over Taiwan highlight the acute security challenges facing Japan. However, Japan’s strategic calculations must now account for a changing landscape where relying on unwavering US support can no longer be assumed. This necessitates a fundamental shift in Japan’s defense planning, moving towards a posture of greater self-reliance and independent capability development.
Changing US Expectations Force Japan to Adapt
The security environment in East Asia is further complicated by the evolving expectations and increasing pressure from the United States for greater burden-sharing in the defense of the Indo-Pacific. The United States has consistently called for increased defense spending by its allies, including Japan. Some analysts have even categorized Japan as being in a “danger zone” concerning its defense spending relative to its GDP and trade balance with the United States, suggesting that Japan could face increased pressure for higher defense expenditures and potential tariffs. The Japanese government has set a goal to increase defense spending from less than 1% to 2% of GDP by 2027 according to its Defense White Paper 2024. Despite improvement, there are concerns that even this may not be sufficient to satisfy US expectations since it falls significantly short of the 5% target advocated by the Trump administration for NATO members, raising the possibility of similar demands being placed on Japan in the near future.
Elbridge Colby, Trump’s nominee for Under Secretary of Defense for Policy, further underscored this concern by publicly stating that Japan’s military capabilities, in both quality and quantity, currently fall short for effective self-defense and regional collective defense through a strategy of denial. A strategy of denial is one that is designed to prevent any power from dominating one of the world’s critical regions, especially its most important region, which is Asia. The primary aim of this strategy is to ensure that no single state becomes so predominant that it could control the US economy, threaten its physical security, and undermine American interests. Colby’s nomination, as a key architect of the 2018 US National Defense Strategy, which prioritized competition with China, and author of “The Strategy of Denial: American Defense in an Age of Great Power Conflict,” thus signals a heightened US focus on Japan’s role within its broader denial strategy.
“Japan should be spending at least 3% of GDP on defense as soon as possible and accelerating the revamp of its military to focus on a denial defense of its own archipelago and collective defense in its region. The best way for the United States to support this shift is to make these priorities and urgency clear to Tokyo in a constructive but pressing fashion.”
Senate Armed Services Committee Advance Policy Questions for Elbridge Colby, Nominee for Appointment to be Under Secretary of Defense for Policy
The challenge for the United States is that it cannot deter PLA aggression unilaterally as it has done in the past, so now a more robust strategy of denial must include allies like Japan. However, since deterring PLA aggression is the America’s top national security priority, it is willing to use both economic and security leavers to get alignment among its allies. As Colby directly states, the most likely strategy the Trump administration will take toward Japan is an urgent consultative strategy, where it prioritizes constructive dialogue and cooperation.
However, if the Trump administration feels that earnest progress is not being made, the United States has other options. They could use tariffs. As a large automobile producer and exporter, Japan is particularly vulnerable to tariffs that target its automotive sector. A second option would be to increase the cost of stationing US forces in Japan, forcing the Japanese to provide economic concessions. Finally, they could threaten to remove US forces from Japan altogether, forcing the Japanese government to make up for the loss of military capabilities.
This threat of looming pressure from the United States creates a significant concern for Japan. It introduces uncertainty into historic guarantee of being under the US security umbrella, which has been a cornerstone of Japan’s defense strategy since the end of World War II. Japan can no longer afford to assume that the United States will automatically bear the primary responsibility for its defense. In the interim, Japan will likely respond to this uncertainty by seeking closer cooperation with the United States while strengthening its domestic defense industry, increasing its defense budget, and diversifying its security partnerships.
Internal Considerations for Japan, Conclusion, Recommendations
The security landscape surrounding Japan has dramatically shifted since the end of World War II, presenting increasingly complex and serious challenges. The PRC’s rapid military modernization is a key driver of regional instability, and has heightened concerns about a potential conflict over Taiwan. Simultaneously, the bedrock of Japan’s defense, the Japan-US Security Treaty, faces uncertainty stemming from ongoing discussions about defense spending and base burden-sharing. Domestically, Japan grapples with a declining birthrate and aging population, straining its ability to maintain a robust defense posture, while low food self-sufficiency introduces additional vulnerabilities.
Addressing these multiple threats means that Japan must fundamentally change its approach to national security. Both the government and the public must embrace a stronger sense of ownership of Japan’s defense. This requires a comprehensive reassessment of the Japan’s self-defense system. To ensure peace and stability in the Indo-Pacific region, Japan must cultivate a more robust and reliable partnership with the United States and actively engage in international cooperation. Crucially, Japan must also undertake significant reforms to its defense structure, addressing personnel shortages, enhancing defense capabilities, and bolstering food self-sufficiency. Strengthening national defense capabilities to enhance deterrence is paramount. This will enable Japan to secure itself, contribute to regional stability, and strategically reduce its reliance on the United States.
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