Making Missile Defense Work for Japan
Members of the Japan Self-Defence Forces stand guard near Patriot Advanced Capability-3 (PAC-3) land-to-air missiles, deployed at the Defense Ministry in Tokyo, Japan, December 7, 2012.
Image Credit: REUTERS/Issei Kato/File Photo

Making Missile Defense Work for Japan


Unique among the militaries of the great powers, the Japanese Self-Defense Forces (SDF) have, by virtue of their symbiotic and treaty-bound relationship with the United States military, been able to operate exclusively as the defensive “shield” of Japan and its interests. With strike power distributed among pacific command and its forces stationed in Japan, the United States military functions as the “sword” in the defense of Japan and the maintenance of stability in East Asia. During the Cold War, the distribution of tasks, tactics and weapons systems between “shield” and “sword” was relatively straightforward. With the primary threat to regional peace being the prospect of Soviet naval vessels sweeping into the Western Pacific, the SDF’s tasks were twofold: ensuring control of the Sea of Japan to bottle up the Soviet Navy close to Russia, and the defense of Hokkaido in case of a massive Soviet amphibious assault. In securing Japan, then, the SDF invested in major ground systems like tanks and artillery, while the Maritime Self-Defense Forces (MSDF) order of battle reflected the MSDF’s primary missions of anti-submarine warfare, mine clearance and auxiliary sea control.

But with the collapse of the Soviet Union and the so-called revolution in military affairs of the early 1990s, the line between “sword” and “shield” began to blur. The major military threat to Japan was no longer the prospect of Soviet tanks pouring into Hokkaido, but rather swarms of North Korean and, later, Chinese theater missiles menacing Japanese cities. Combating this threat has meant re-evaluating the technological and doctrinal limits of a “shield” military. The prospect of missile attack, beginning with DPRK ballistic missile launched over Japan in 1998, has been one of the key catalysts pushing the Japanese military to operate in new domains and purchase new systems. With the threat increasing in technological sophistication and reaching new heights of provocation, Japan’s defense ministry recently ordered a three month round-the-clock missile defense surveillance mission, a supposedly unprecedented operation. What does this mission mean for Japan’s ballistic missile defense (BMD) strategy and systems? How can the United States, Japan’s most powerful and oldest ally, be a good alliance steward in ensuring the effective execution of this mission?

Understanding BMD in the Japanese Context

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In the popular consciousness, missile defense most often conjures the image of the proverbial “bullet hitting a bullet”: a friendly interceptor missile destroying the adversary projectile through kinetic or explosive energy. Newsroom-ready images of Patriot missiles slamming into Iraqi Scuds were beamed into American living rooms during the Gulf War. Similarly, every new DPRK missile launch brings with it an NHK broadcast of Patriot batteries deployed in front of the defense ministry headquarters in Tokyo. These images are not misleading, but as Jon Solomon explains in an excellent write-up of BMD strategy at CIMSEC, anti-missile warfare is more than just the sharp end of the spear. It encompasses warfare and strategy that is far deeper than the final bullet-hitting-a-bullet interception. These ten “threads” of anti-missile warfare are a useful lens with which one may analyze Japan’s BMD strategy. They are:

  1. Suppress missile-armed platforms’ basing and logistical support infrastructure
  2. Defeat the systems-of-systems that missile-armed mobile platforms rely upon to attack effectively
  3. Defeat missile-armed mobile platforms as they break out of their bases/garrisons towards their firing positions
  4. Defeat missile-armed air and naval platforms in choke points
  5. Defeat missile-armed mobile platforms in their patrol or firing areas
  6. Induce missile-armed mobile platforms to fire at false targets and perhaps expose themselves to attack
  7. Mask our forces from the adversary’s local reconnaissance and targeting efforts
  8. Defeat missile-armed air and naval platforms in close battle
  9. Defeat the inbound missile
  10. Create conditions where an adversary chooses not to employ theater missiles

With the ninth article of Japan’s constitution precluding the purchase of any true long-range strike weapons like cruise missiles or bomber aircraft, the fulfillment of threads 1 and 3 is beyond the scope of Japan’s current defense capability. However, the remaining threads underscore how for even a “pacifist” country like Japan, missile defense is more than just the final moment of interception (or thread 9). To properly execute the mission, each thread must lead to the next, with political and military leaders receiving timely and accurate information each step of the way. The Japanese government’s response to DPRK missile launches in recent days points to significant gaps in this “patchwork” of missile defense threads, gaps that must be rectified if BMD is to be made a realistic possibility for Japan.

On 3 August, a pair of Nodong medium-range ballistic missiles launched from North Korea breached Japan’s exclusive economic zone (EEZ) and landed only 250 km from Akita prefecture in northern Honshu. In missile-travel terms, then, the Nodongs were only a couple of extra seconds from impact in Japan. Disturbingly, the Japanese edition of the Mainichi Shimbun quoted an unnamed government official as saying: “Had the missile continued to fly into Japanese territory, we would probably be unable to shoot it down.” Further, the Washington Post’s Anna Fifield, in a recent article on advancements to the DPRK missile program, quotes a Nikkei report stating that Japan was unable to detect North Korea’s launch of three short-range missiles in the wake of the recent G-20 conference in Hangzhou, China. Another Mainichi report explains how while the Maritime SDF has four Aegis-equipped destroyers capable of BMD operations, only three can be deployed at any one time due to maintenance and scheduling needs.

These deficiencies, in domain awareness and interceptor coverage, mean that defense minister Inada’s recent order to the SDF to be maximally ready for BMD operations for three months straight is more likely a political rather than tactical move. While the LDP and Inada (frequently mentioned as a future candidate for prime minister) must undoubtedly look tough in response to a mounting DPRK (and Chinese) missile threat, the three-month readiness period would undoubtedly be best served by filling in gaps in Japan’s sensor capabilities and beefing up the deployment of Patriot Advanced Capability-3 (PAC-3) and Aegis-capable destroyers. Heartingly, this appears to be the current direction of Japanese policy. The defense ministry has requested a record-high budget with specific provisions for enhanced PAC-3 missiles and other BMD components. Minister Inada has also spoken recently about the need for Japan to procure both the terminal high altitude area defense (THAAD) system and Aegis Ashore, two systems that will allow Japan to intercept ballistic and cruise missiles farther away from Japanese territory. These changes are necessary if Japan is to fulfill thread 9 on its own, the keystone of any meaningful BMD effort and the backbone of thread 10, deterring an adversary from usage of theater missiles.

But what of the other threads, especially those which Japan is unable to fulfill on its own (like 1 and 3)? It is here where Japan’s key alliance, that with the United States, comes into play.

Being a good alliance steward: America’s role in Japan’s BMD effort

With thousands of troops and billions of dollars in military equipment stationed in Japanese territory, America has a marked stake in Japan’s BMD mission. American and Japanese firms have co-developed the PAC-3 and its seaborne counterpart, the Standard missile (not to mention the Aegis combat system underpinning Japan’s Kongo and Atago class BMD destroyers). BMD was explicitly mentioned in new alliance guidelines between Japan and the United States as an area for the exercise of “collective self-defense.” In helping its ally execute the BMD mission, America’s role is twofold: filling in the gaps of the BMD “patchwork” where Japan is restricted by its constitution, and gently pushing Japan to expand the kinds of missions it can execute.

To accomplish the first aim, America must coordinate closely with Japan to delegate alliance responsibilities for BMD missions. Indeed, many of the needed changes to consultation mechanisms and operational guidelines are taking place between the allies. The recent changes to the U.S.-Japan alliance guidelines specify the creation of a standing alliance coordination mechanism (ACM), which covers BMD up and down the chain of command. A U.S. military representative in Japan underscored to me in a recent interview that close consultations between the United States and Japan support the formation of a bilateral “critical asset list;” the list of civilian and military facilities in Japan that both America and Japan will defend. These kinds of consultations and mechanisms are needed to ensure that scarce BMD resources, like interceptor missiles and Aegis destroyers, are not deployed redundantly (leaving critical infrastructure undefended).

America’s role as the “sword” of Japan gives it a comparative advantage in defeating adversary mobile missile systems. While theater missiles could only be launched from expensive and immobile gantries in the past, China and North Korea have begun fielding the majority of their missiles on hard-to-find transporter erector launchers (TELs) with sophisticated liquid fueling systems. TEL-launched missiles, along with their air and sea counterparts, are a formidable problem for the alliance’s BMD mission. Uniquely American power-projection capabilities like aircraft carriers, stealth bombers and low-observable cruise missiles mean that American forces, in consultation with their Japanese partners, are likely most suited for threads 1 and 3. But Japan’s submarine force, especially its air-independent propulsion equipped Soryu class, are especially adept at hiding in littoral seas. These stealthy submarines, together with the placement of anti-ship missiles on far-flung Japanese islands and Japan’s strong anti-submarine warfare capabilities mean that Japan can likely defeat adversary mobile missile systems in choke points, satisfying thread 4. Both allies can work in concert, with good operational security, to accomplish threads pertaining to deception and disguising critical infrastructure from the adversary. Similar cooperation should occur in the cyber domain to both protect friendly systems and to attack adversary networks of BMD systems and their targeting platforms, so-called “systems of systems.” Finally, the Americans should push for the adoption of joint U.S.-Japan BMD cruises in the Sea of Japan to ensure that the recent three month standing BMD order can be successfully executed.

The second aim is more long-term in scope, but echoes much of Japanese defense policymaking since the end of the occupation: the gradual expansion of legal missions and responsibilities for the SDF. This has been a trend since the establishment of Japan’s police reserve force in 1952 over the objections of pacifists and communists. However, BMD has been the reason behind many of the SDF’s most groundbreaking operational shifts over the last 20 years. While the U.S. military official I spoke with described the negotiation process behind the more equal alliance guidelines and collective self-defense as “like opening an inch-wide hole in a dam,” Japanese fears over a lack of BMD capability in response to the 1998 DPRK missile overflight crisis led to the Japanese government explicitly authorizing the SDF to utilize space-based systems for defense. Indeed, the addition of a new domain to the SDF’s areas of responsibility occurred with zero American prodding or powerplaying. These same fears led to the first cracks in Japan’s “three principles of arms exports,” allowing Japan to export defensive systems for the first time in order to co-develop new generations of interceptor missiles with the United States. The Americans should work within the BMD framework to accelerate and encourage this trend. Next steps could include joint BMD patrols in the Sea of Japan, or better trilateral coordination and information sharing between Japan, the United States and South Korea regarding the DPRK missile threat. The fact that now all three nations utilize the Aegis fire-control system for their BMD destroyers could pave the way for limited operational cooperation in intelligence gathering and BMD maneuvers at sea. The annual trilateral Pacific Dragon BMD exercise, while useful in introducing common procedures and operations among the three navies for BMD, should be expanded to involve the actual test firing of interceptor missiles. Recent news pointing to the possibility of sharing THAAD radar data among the US, ROK and Japan is an encouraging, if first, step towards enhanced trilateral information sharing.


Juxtaposing the threat posed by recent DPRK missile provocations directed at Japan with the Japanese government’s response illustrates how the SDF is yet fulfill all “threads” of anti-missile warfare. A lack of BMD systems like Aegis destroyers and PAC-3 batteries, coupled with gaps in Japan’s early warning radar and satellite network, means that the recent MoD order for a three month BMD standby is more political tough talk than operational reality. The government is keenly aware of these issues, however, and the defense ministry has requested record high BMD budgets for the purchase of new systems and interceptors.

Properly connecting the BMD threads and executing the mission, in which decision makers will have mere minutes even under the best of circumstances, means consultation with the United States is critical. With its own personnel and equipment sure to be in the crosshairs, America should both assume responsibility for the “threads” Japan is constitutionally unable to pursue and must encourage a greater role for the SDF. Using the momentum provided by recent Japan-South Korea efforts at reconciliation and BMD’s expansionary role in Japanese defense policymaking, America should work towards greater trilateral cooperation between its most powerful Asian allies, at least pertaining to the BMD mission.

The revolution in military affairs undoubtedly sped up the pace of contemporary warfare, and has led to the development of fast and destructive precision weapons. For as difficult as missile interception is, however, the keystone of the revolution in military affairs, information (whether known as C4ISR, “informationalized warfare” or other such monikers for command and control of disparate targeting, intelligence and firing platforms), means that the defender has the option of cutting links in a “kill chain” rather than simply waiting for the moment of final interception. Together with its ally the United States, and in conjunction with new partners like South Korea, Japan can move ahead with a cost-effective and comprehensive means of addressing the “threads” of missile defense.

Ben Rimland is a second year MPhil student of modern Japanese studies at St. Antony’s College, University of Oxford. He researches Japanese defense policy, the US-Japan alliance, and East Asia defense issues. Ben is concurrently a Young Leader at Pacific Forum CSIS. He tweets at @brim1and.

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