On April 10, Japan and the United States reached a historic agreement to upgrade their relationship to “global partners,” a remarkable transformation from their status as adversaries in World War II over 80 years ago. This new partnership encompasses several new strategic initiatives, with the two nations agreeing to collaborate and share resources across a wide range of areas, from defense and technology to climate and diplomacy. Importantly, the recent joint statement reflects an emerging recognition that climate change poses complex security challenges requiring enhanced Japan-U.S. defense and security cooperation.
Climate change as a security issue does not receive as much attention in Japan’s national security planning and operations. Japan’s latest National Security Strategy (NSS), published in 2022, marked a milestone as it recognized for the first time that “climate change is a security issue that affects the very existence of humankind.” The climate-security nexus is also covered in its first paragraph with the statement that “a host of issues such as climate change… are emerging, requiring cross-border cooperation among nations” as they impact “Japan’s national security in various ways.”
Alongside the strategic-level recognition of climate security, the Japanese defense sector has taken more concrete steps. In 2022, the Ministry of Defense (MoD) established a Response Strategy on Climate Change, which outlined 10 measures to address three main objectives (1) adaptation and response to the future impacts of climate change, (2) carbon neutrality, and (3) greenhouse gas reduction within the defense sector. This initiative followed the MoD’s establishment of a Climate Change Taskforce in 2021. These developments are important as they show the MoD’s recognition that the efforts to address climate change is compatible with military capabilities and operations.
Despite these positive developments, translating this rhetoric into tangible action has been challenging. This is evident in the overall tone of Japan’s latest NSS, where concerns are still largely dominated by geopolitical and traditional security issues. Japan’s traditional security mindset, which prioritizes threats such as Russia and China, makes it challenging to incorporate climate risks into established security frameworks.
Prime Minister Kishida Fumio has certainly focused on strengthening Japan’s defensive capabilities amid growing concerns about China’s assertiveness and North Korean provocations. Recently, his government has also approved a record 7.95 trillion yen (approximately $55.9 billion) defense budget for the fiscal year 2024. However, the climate-security nexus has still received less attention from his administration. In this, there is an opportunity for Japan to deepen integration with the U.S. security agenda and strengthen its role as a global partner for the future.
In contrast, the United States has positioned climate change as a security issue at the forefront of its national security planning and operations over the past two decades, with the Obama and Biden administrations making significant strides in securitizing climate change. Notably, the U.S. 2022 NSS identified climate change as the “shared problem” that is “the greatest and potentially existential for all nations,” placing it at the center of national security policymaking to an unprecedented extent alongside strategic competition with China and Russia, and the importance of domestic industrial policy and investment. It also recognized the Indo-Pacific as the “epicenter of the climate crisis,” and “essential to climate solutions.”
This focus on the climate-security nexus continued in the U.S. 2022 National Defense Strategy (NDS), which underscored its importance in national security strategy and planning. The NDS explicitly recognized climate change as a “dangerous transboundary threat” that is transforming the operational context for the U.S. Department of Defense. By prioritizing resilience and adaptability, as well as integrating climate change into threat assessments, the NDS firmly established climate change as a critical security issue for the U.S. defense sector.
Meanwhile, as a “threat multiplier,” climate change risks exacerbating existing tensions, instability, and conflicts in the Indo-Pacific region by increasing competition over scarce resources. Fisheries, in particular, are a flashpoint for conflict. Declining fish stocks due to overfishing and climate change are a major concern in the Indo-Pacific region, where many countries rely heavily on fisheries for food and livelihoods. This scarcity could exacerbate existing maritime disputes and territorial conflicts in the region.
In the midst of this, China, which operates the world’s largest distant-water fishing fleet, has been accused of engaging in widespread illegal, unreported, and unregulated fishing practices. These practices deplete fish stocks in the exclusive economic zones of neighboring countries. As fish populations continue to decline, competition for the remaining resources could increase tensions and potential conflict between China and rival claimants in the region.
The South China Sea, a region rich in marine biodiversity, is a particular hotspot. Overfishing and climate change have severely depleted fish stocks in the region. China has imposed an annual summer fishing ban in the South China Sea since 1999, which it claims is to promote sustainable marine fishery development and improve ecology. However, Vietnam and the Philippines have criticized the ban as violating their sovereignty over the disputed Paracel and Spratly Islands and surrounding waters. Tensions further escalated in 2020 when a China Coast Guard (CCG) ship rammed and sank a Vietnamese fishing boat in the disputed waters. In 2022, these countries condemned the ban and urged their governments to resist it, as it impacts the livelihoods of their fishermen, though defying the ban could result in confrontations with the CCG.
In response to these challenges, closer Japan-U.S. cooperation on climate security can serve as a counterbalance. It can help counter activities that undermine established legal orders to maintain regional stability, deter potential conflicts, and protect their shared vision for a free and open Indo-Pacific. Building on this, the prospect of Japan aligning more closely with the U.S. on the climate security agenda can help advance Japan on two major fronts.
First, with the U.S. military already at the forefront of addressing climate change threats, Japan can benefit from the United States’ experience in this area. This could involve increased military-to-military cooperation on the response and adaptation of military infrastructure and operations to the impacts of climate change, and intelligence sharing on climate-related risks. Such collaboration can help strengthen Japan’s military capabilities and allow the two allies to better prepare for and respond to shared vulnerabilities.
For instance, the U.S. military’s approach to climate change, which includes incorporating “climate literacy” into its training programs and increasing cold-weather training exercises due to the Arctic’s strategic importance, offers valuable lessons for Japan to prepare its personnel for operating in climatic conditions impacted by climate change.
Additionally, the U.S. military’s proactive response to climate-induced disasters, such as considering climate impacts in basing decisions, planning for environmental changes at coastal installations, and analyzing impacts of major climate disasters such as Hurricane Michael on Tyndall Air Force Base (AFB) and flooding at Offutt AFB, provides opportunities for sharing intelligence, analyses, and best practices between Japan and the United States.
Second, the climate security agenda can be a useful diplomatic tool for Japan to enhance its presence and influence in the Indo Pacific region. Japan already aims to assist island nations and other developing countries in the region where climate change poses imminent threats in building sustainable and resilient economies and societies, as mentioned in its NSS 2022. Closer cooperation with the U.S. on climate security means that Japan can leverage the U.S. resources and capabilities to enhance climate resilience and adaptation efforts in third countries.
One potential strategy could involve the U.S. providing financial, technical, and technological assistance to Japan’s Asia-Pacific Climate Change Adaptation Information Platform (AP-Plat) launched by Japan’s Ministry of Environment in 2019 to provide Asia-Pacific countries with data on climate effects, thereby supporting climate-informed policies and effective climate adaptation in the region. This can support not only regional stability but also Japan’s strategic interests as an indispensable stabilizing power.
For Japan to be a true “global partner” with the U.S., it needs to closely align its understanding and approach to climate change threats to its most important ally. Otherwise, deepening defense and security cooperation between the two countries will be challenging if they have divergent risk assessments and priorities. By elevating and closely aligning its climate security agenda with that of the United States, Japan can firmly establish itself not just as a “global partner” alongside the U.S., but as an agenda-setting leader amid accelerating climate impacts.