How Might Japan Join the Five Eyes?

The release of a new Japanese National Security Strategy last month (the first since 2013) has been described by observers as “drastic,” likely to “shatter policy norms” in place since World War II. This, combined with discussions in Japan’s media on raising defense spending to 2 percent of GDP, reveal a bilateral consensus that the alliance needs to be improved in the area of command-and-control to provide deterrence in a rapidly declining security environment, vis à vis China. There are increasing calls from inside both governments—and outside government—for the United States and Japan to increase intelligence sharing since war planning requires a much higher level of information sharing between militaries. As a result of this, a separate but related question is being asked as to whether Japan should be included in the preeminent intelligence-sharing group, the Five Eyes.

While the intelligence network—composed of Australia, Canada, New Zealand, the United Kingdom, and the United States—has its origins tracing back to World War II, the rise of an assertive China in the Indo-Pacific provides a growing rationale for Tokyo’s accession to the group. After all, the Five Eyes began due to an increasing need to share intelligence at a much higher level for more effective war planning. Prominent figures on both sides of the Pacific have advocated for Japan’s inclusion as security in the region has deteriorated. Former Japanese defense minister Taro Kono made the case in 2020, with a group of prominent U.S. experts adding their voice in a prominent 2020 CSIS study. Japan has deepened strong intelligence-sharing relationships with different members of the Five Eyes—most recently with Canada—there are still no signs that it will be invited into broader group arrangements. In many ways, there are complexities in the broader remit of the group beyond those of intelligence sharing that should be addressed prior to any accession.


First, Japanese policy elites should understand that the original Five Eyes framework has long since evolved beyond the original remit of signals intelligence sharing to encompass a range of formal and informal information sharing arrangements and policy alignment meetings. The range of activities that fall under the rubric of Five Eyes is so wide-ranging and decentralized, that as a practical matter, it is questionable as to whether Japan would want to join. For example, there are hundreds of existing agreements and working groups outside of the intelligence spheres, such as in the defense and diplomacy spheres, where equipment interoperability, military information sharing, and foreign ministry dialogues occur. Indeed, Japan has been added to some of these on an ad hoc basis.

There are many activities that take place in the domestic security sector, such as the Quintet group of Attorneys General and the Five Country Ministerial (FCM) that look at border security, law enforcement, cybersecurity, and immigration. A 2021 study found that security practitioners and experts from across the five are predicting even newer forms cooperation outside of the intelligence community due to the growing non-kinetic challenges posed by China and Russia. Much of this cooperation would address nontraditional security sectors, such as cyber, supply chain, and information operations. A number of experts interviewed for the study advocated that the five strengthen their technological research and development and industrial integration through the National Technology Industrial Base to counter China’s scale advantage. While the five nations are not the only grouping for such cooperation—the Quad, AUKUS, G7, and the North Atlantic Treaty Organization (NATO) also play a role—the grouping’s historic intimacy and comfort working in sensitive information-sharing spaces lends itself well to dual-use technological co-development. Thus, when thinking of joining the Five Eyes, Japan should consider to what extent it wishes to integrate with the other five across these non-intelligence community areas.

Secondly, when it comes to accessing the Five Eyes intelligence community, Japanese elites deserve a clear understanding of what is required of them before they can access this inner of inner rings. It is not simply a case of regular exchanges between intelligence agencies, but rather a level of institutionalized information sharing that occurs across multiple agencies and departments. As with those nations that wished to join NATO, there is a clear pathway to adopting “five eye standards” that would greatly facilitate the political decision of membership or at least an equivalent level of intelligence sharing and cooperation. Broadly speaking, these five eye standards exist in three broad “baskets.” The first of these is the clearance and vetting system that all five have developed to better enable who can access classified information, including the most sensitive information. If Japan wishes to join the Five Eyes intelligence community, it should understand the standards that all Five Eyes partners meet and develop a department that runs a universal process of vetting government personnel with access to information that is classified by common standards and procedures. Such vetting affords personnel different levels of clearance, which in turn affords the level of access to classified information. In addition to being applied to civil servants across the government, members of the military, and select members of industry, such vetting and clearance should be applied to those Diet members involved in parliamentary oversight of the intelligence apparatus.

The second basket is that of classification itself. Probably the bedrock for intelligence sharing, classification allows information to be put into a hierarchy according to secrecy. When paired with the clearance system, classification allows for safe information sharing across bureaucracies. Japan should adopt a classification ranking system that approximates the one used by the five nations. Again, this should be applied across all Japanese departments and agencies since different classification systems within different bureaucracies hinder information sharing. The third basket is that of information-sharing standard operating procedures, in which data is shared according to certain processes. In order to join the SECRET and TOP SECRET networks operated by the Five Eyes, Japan would have to put in place certain safeguards with regard to cybersecurity and user security. Again, this would require that users are vetted and adhere to the common cybersecurity practices applied by the other five.

In terms of joining the Five Eyes, Japanese elites should think of where they want to go and understand to what extent the Five Eyes will help them get there. If their intent is to develop closer intelligence with the United States so as to deter Chinese military adventurism in the Indo-Pacific region, joining the group need not necessarily be the end goal. Closer and deeper institutionalization between U.S. intelligence and Japanese intelligence actors can be done on a separate track from those relationships with UK, Australian, and Canadian intelligence agencies. On the other hand, if Japan wishes to align more deeply with the Five Eyes for a broader strategic relationship—one that will be measured in decades—then joining various parts of the group, including the intelligence community part, is desirable. The strongest reasons for Japan’s accession to the Five Eyes is not its alignment over China but its long-term alignment with the United States dating back seven decades and a desire to integrate more deeply with the broader strategic community to which the United States belongs. As mentioned, the five collaborate across many different fields at a level that is astonishing to outsides, but nearly taken for granted within the five. Japan would have to learn to be comfortable with that.

If Japanese policymakers decide that they wish to continue this integration at the intelligence-sharing level—and deepen it—then political will is required to make the necessary changes across Japan’s bureaucracy. These include creating the machinery for vetting and clearance, classification, and information-sharing procedures and then applying those across government, industry, and the Diet. Broadly speaking, Japan needs to initiate internal changes and adopt similar cyber hygiene standards to those applied across the Five Eyes nations. This doesn’t mean Japan needs to build exact replicas, but rather Japan-specific approximations. A historical parallel is the long process by which Eastern European states implemented structural reforms of their militaries and security sectors in their desire to accede to NATO. Given the rise of global instability and the diffusion of attack vectors into Western societies, Japan stands to gain by its accession to the Five Eyes—and the group would certainly gain by the inclusion of the world’s third-largest economy and third-largest military force in the Indo-Pacific region. It would also gain by Japan’s historic intelligence gathering on North Korea and China, while Japan would widen its understanding of other regions. What is required now is for the Five Eyes to quietly lay out that roadmap for accession so that Japanese officials understand what is required.

John Hemmings is senior director for Indo-Pacific foreign and security policy at Pacific Forum and an adjunct fellow with the Japan Chair at the Center for Strategic and International Studies in Washington, D.C.

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