Key Challenges in Japan’s Defense Policy

From the Views from the Next Generation Series
Policy briefs by Japanese security experts on Japan’s core security issues, from emerging domains to enduring challenges
By Yuki Tatsumi Editor  ·  Pamela Kennedy Editor  ·  Jason Li Editing Support  ·  Taro Sato Author  ·  Yoshimitsu Sato Author

Japan is concentrating its efforts to reconceptualize its national defense to meet a modern, more uncertain security environment. The release of the 2018 National Defense Program Guidelines emphasizes that preserving stability and maintaining a rules-based order within the Indo-Pacific region requires Japan to take a forward role in adapting to rapid challenges ahead. Still, questions linger around Japan’s ability to work around constitutional constraints, an aging population, and alliance demands. Despite these concerns, Japan has avenues and opportunities to develop its defensive capabilities in close cooperation with the United States and other partners. Key Challenges in Japan’s Defense Policy presents fresh and insightful reports from Japanese experts on core security issues—from emerging domains like cyberspace and outer space to enduring challenges of strategic competition, deterrence, and demographic change—that it must undertake in the coming years.

Part of the Japanese Foreign Policy Project

On January 19, 2020, the United States and Japan celebrated the 60th anniversary of the signing of the U.S.-Japan Mutual Security Treaty. The foreign and defense ministries of the two countries recognized this occasion by issuing a Joint Statement on January 17, followed by celebratory messages from U.S. President Donald Trump and Japanese Prime Minister Shinzo Abe, commemorating the “peace, security, and prosperity” enabled by the “pillar immoveable” that is the alliance.[i]

Through these statements, the two governments sent two significant messages: (1) the U.S.-Japan alliance is more critical than ever for the peace and prosperity of the Indo-Pacific region and beyond, and (2) the two governments are committed to continuing to strengthen the alliance. From Tokyo’s perspective, one of the critical components of Japan’s own effort to reinforce the alliance is to continue to modernize its defense capability to better meet the security challenges of today and the future. In this context, Japan released two key defense policy-planning documents in December 2018: the National Defense Program Guidelines (NDPG), a policy document that guides Japan’s defense policy for the next five years, and the Mid-Term Defense Program, an acquisition planning document that supports the NDPG.

The 2018 NDPG put out “Multidomain Defense Force (tajigen tōgō bōei-ryoku)”as an organizing concept that Japan will strive towards. Explained as deepening the concept of a “Dynamic Joint Defense Force (dōteki bōei-ryoku)” that was laid out in the 2013 NDPG, this new concept is supposed to serve as a vision that guides the effort to better prepare Japan to effectively meet the security challenges that Japan will face over the next several years.[ii]

At the time of the release, the reference made in the NDPG to the possibility of acquiring long-range missile capability and the clear indication of Japan’s intention to acquire an aircraft carrier attracted intense media attention. However, the document highlighted other domains as the new priority for Japan’s defense-planners: space, cyberspace, and the electromagnetic spectrum.

Some of these “new” domains identified are not new to the 2018 NDPG. In fact, the 2013 NDPG already identified space and cyberspace as emerging battle domains that can potentially affect the operation of the Japan Self-Defense Forces (SDF) considerably. However, while these domains’ importance to the SDF’s future operational environment was mentioned, investment in these areas was not prioritized. What makes the 2018 NDPG’s emphasis on these areas, along with the electromagnetic spectrum, different from previous defense policy iterations is that they are identified as critical enablers for future SDF operations in cross-domain environments and acknowledged as high-priority areas of investment.

The 2018 NDPG also reiterates that the security environment in Japan’s immediate neighborhood continues to degrade, stressing the importance of continuing to strengthen Japan’s alliance with the United States. In addition, the NDPG discusses the need for Japan to continue to expand its security cooperation with other likeminded countries, particularly in the Indo-Pacific region. Indeed, the security environment that Japan—and the U.S.-Japan alliance broadly—faces is changing at an accelerated speed, its unpredictability quickly growing. In addition to the threats that have consistently been present, such as North Korea’s nuclear and missile program and China’s growing aggressive behavior, and the impact of emerging technologies in the battlespace, Japan finds itself in a security environment that is becoming less and less safe, particularly given the perceived declining commitment of the U.S. in the region. Given such circumstances, analyses that carefully examine how Japan plans to meet these challenges are indeed appropriate. That is why Stimson’s Japan Program decided to “go back to the basics” and chose key challenges for Japan’s defense policy, as identified and highlighted in the 2018 NDPG, as the theme for this year’s edition of the Views from the Next Generation series.

[i] Trump, Donald J. “Statement from the President on the 60th Anniversary of the United States-Japan Treaty of Mutual Cooperation and Security.” The White House. January 18, 2020.
Abe, Shinzo. “Remarks by the Prime Minister, Marking the 60th Anniversary of the Signing of the Japan-U.S. Security Treaty.” Kantei. 19 January 2020.

[ii] Ministry of Defense of Japan. “Heisei 31 nendo ikō ni kakaru bōei keikaku no taikō ni tsuite” 平成 31 年度以降に係る防衛計画の大綱について [Outline of defense plan for FY2019 and beyond]. December 18, 2018. 9-10. NB: The title of this document is translated as the “National Defense Program Guidelines for FY2019 and beyond.” See the provisional translation at:

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