Japan’s Potential Acquisition of Ground-Launched Land-Attack Missiles: Implications for the U.S.-Japanese Alliance
In late August 2017, millions of people in northern Japan got a startling, early morning text message. “Missile alert,” it read, before telling people to take cover. North Korea had launched a ballistic missile, which flew over Japan’s northern island of Hokkaido before landing in the sea. Two weeks later, North Korea fired another missile through Japanese airspace. Pyongyang’s provocations are not the only ones that have been making Japanese policymakers anxious. Although China has been active in the waters and airspace near Japanese territory for a long time, over the last several years, the level and types of activity have increased. In the air, for example, Japanese fighters are scrambling almost twice per day in response to Chinese military aircraft entering Japan’s Air Defense Identification Zone.
In light of the current security environment, many Japanese decision-makers have been looking for ways to bolster deterrence using their country’s own defense capabilities. One option, although still in the realm of the theoretical, includes the acquisition of ground-launched land-attack missiles. Japanese policymakers eschew the terms “long-range strike” and “offensive strike.” Instead, they describe such missile capabilities using terms like “deterrence” or “self-defense,” an approach that dates back to the 1950s when the Ichiro Hatoyama administration said the spirit of the constitution did not mean the government had to “sit and wait to die” in the event of a missile attack. Although the Hatoyama administration did not specifically refer to missile capabilities, the statement has been recognized as providing a legal basis for the acquisition of capabilities to strike foreign bases. While the debate among Japanese policymakers over whether the country should acquire ground-attack missiles never completely disappeared over the subsequent years, it focused largely on the legal considerations related to possession of such weapons.
In the late 1990s, after North Korea demonstrated an ability to strike Japan, the debate began to move beyond theoretical legal discussions to focus on the operational rationales for having strike capabilities. The most recent iteration of this debate began in March 2017, when Japan’s ruling Liberal Democratic Party started to examine the issue of acquiring “enemy base attack capability.” Subsequently, after the Shinzo Abe administration decided to suspend deployment of two Aegis Ashore systems in June 2020, many Japanese policymakers became more focused on how to enhance the country’s capacity to deter. Concern over China’s threat to Taiwan and its implications for Japan’s security has further fueled Japanese decision-makers’ interest in missiles, as have North Korea’s advancing strategic and conventional capabilities, including a purported new type of tactical guided missile.
Most of the analysis and commentary about Japanese policymakers’ recent interest in procuring ground-based strike missiles has focused on the deterrent advantages they would provide. While these discussions cogently assess how such weapons might affect adversaries’ calculations, they rarely consider the broader potential consequences that Japanese procurement of strike capabilities may have for the U.S.-Japanese alliance. In reality, any Japanese acquisition of such weapons could carry substantial implications for the alliance in relation to planning, operations, and procurement decisions. Those implications merit greater debate, discussion, and planning among Japanese and American policymakers.
Japan’s Dangerous Neighborhood
As Japan’s National Security Strategy describes it, the country’s surrounding region is becoming “ever more severe.” Retired Lt. Gen. Koichi Isobe, who served in the Ground Self-Defense Force, notes that the past decade has been the first time Japan has ever been forced to confront threats from the north, the Korean Peninsula, and the southwest islands simultaneously.
While North Korea has kidnapped Japanese nationals, intruded into Japanese waters with spy ships, and fired ballistic missiles over and toward Japan, it is Pyongyang’s advancing nuclear weapons and delivery systems that are the most alarming for Tokyo. North Korea’s capabilities are growing in number and diversity, and they constitute “grave and imminent threats to Japan’s security,” in the words of the 2021 Defense of Japan white paper.
China’s rapidly modernizing armed forces represent perhaps an even greater threat to Japan, one that ranges from the “gray zone” to the nuclear realm, including in the so-called “new domains” of space, cyber, and the electromagnetic spectrum. In addition to Chinese military aircraft entering Japan’s Air Defense Identification Zone, Chinese vessels are routinely sailing in Japanese waters, including its territorial waters. These activities stress both Japan’s Coast Guard and its Self-Defense Forces.
These increasingly frequent instances of Chinese coercion, alongside similar actions directed against Taiwan, have led some Japanese Diet members to propose reinforcing ties between Japan and Taiwan in an effort to dissuade China from pressuring Taiwan. And the summary of Tokyo’s latest defense white paper states that “stabilizing the situation surrounding Taiwan is important for Japan’s security and the stability of the international community,” reinforcing recent public signals from senior figures in the Japanese defense establishment that the country has a national interest in Taiwan’s security.
As the risks to Japan’s security appear to grow, the public debate in Japan increasingly focuses on how best to reinforce deterrence. Some argue that deterrence by denial might be sufficient to dissuade Beijing or Pyongyang from taking aggressive actions. Others, however, argue that Japan should consider the desirability of procuring strike capabilities that would allow the Self-Defense Forces to enhance deterrence through the threat of punishment.
Japan’s Current Missiles
Japan’s Self-Defense Forces are modern armed forces with advanced capabilities, including a newly introduced capacity for amphibious operations in defense of the country’s remote islands. While the Self-Defense Forces possess the ability to hold enemy platforms at risk from the air or sea, they do not possess ground-launched ballistic or cruise missiles with sufficient ranges to strike an adversary’s territory, and even their capabilities for targeting air and naval platforms are of limited range.
According to open sources, Japan’s current Type-03 surface-to-air missiles have a range of 31 miles, and an upgraded version currently under development will extend that to 62 miles. Similarly, starting in 2019, the Self-Defense Forces began deploying advanced Type-12 anti-ship cruise missile batteries at selected sites across the country’s southwest island chain, but these have a maximum range of only 124 miles. In 2019, it was reported that the range of these missiles would also be extended, to 560 miles. Assuming the Japanese government meets the goals it set out for itself in its most recent Mid-Term Defense Program, by 2023, the Self-Defense Forces will field more strike options from the air, specifically Joint Strike Missiles (with a range of approximately 172 miles) and the Joint Air-to-Surface Standoff Missile-Extended Range (approximately 620 miles).
These capabilities all have the potential to deliver a munitions package far from Japanese territory, but they lack the advantages of ground-based missiles, such as survivability and deeper magazines. In analyzing the implications of Japanese ground-launched missiles for the U.S.-Japanese alliance, we limit our focus to the potential consequences of any decision by the Japanese government to acquire missiles like ground-launched variants of Tomahawks or medium-range ballistic missiles. Although the maximum ranges of such missiles are currently unknown as they are not yet developed, a useful point of reference is what the United States is hoping to develop and deploy. According to early reports, Washington is planning on a ground-launched variant of the Tomahawk and a ground-launched ballistic missile that could have maximum ranges of 620 miles and 2,485 miles, respectively.
If Japan acquired missiles with similar ranges, depending on their deployment, Japan could strike Chinese and North Korean territory. For example, the distance from the Japanese island of Okinawa, where there is a concentration of U.S. and Japanese armed forces, to China’s east coast is approximately 550 miles. And from any of the Self-Defense Force bases in northern Kyushu, such as Ainoura, Sasebo, or Kasuga, Pyongyang is about 460 miles away. From these same locations, Beijing is approximately 870 miles away. If Japan acquired missiles possibly capable of reaching three times that distance, large strategic areas of both China and North Korea would be well within range of them.
Consequences for the U.S.-Japanese Alliance
It is Japan’s sovereign right to decide whether or not to pursue ground-based strike options. Given the country’s various constitutional, legal, and policy restrictions on certain types of capabilities and the ability to use force, acquisition of ground-based missiles that can hit another country would likely require the government to characterize these as defensive weapons or “standoff missiles.” That, however, would only be the first step. Attaining these new capabilities would carry significant consequences for the alliance between the United States and Japan in areas like planning, operations, and procurement decisions. These become clear when considering two hypothetical scenarios.
The first is one often mentioned by Japanese officials as a hypothetical case for when Japan could use strike capabilities: North Korea preparing to launch, or already having launched, missiles at Japan. While Japan’s right to act in self-defense is indisputable, evaluating this scenario raises questions for the United States and Japan that would need to be resolved. In considering any North Korean scenario where Pyongyang has initiated hostilities, Japanese policymakers should work on the assumption that South Korea and the United States would be involved. If Japanese decision-makers are willing to consider strikes against North Korean missile pads, their U.S. counterparts would want to ensure that America avoids getting pulled into executing any plan that is not of its own choosing. Additionally, American policymakers would likely want to coordinate and incorporate potential Japanese plans into existing U.S.-South Korean operational plans and approved target lists. And because Japanese missiles may fly over South Korea — or provoke an attack against that country by North Korea, which might decide to counter threats to its south — Tokyo’s plan would need to be coordinated with Seoul or at least with Washington.
The problem, however, is that Japan is not included in U.S.-South Korean planning efforts. Regardless of the state of Japanese-South Korean ties, the United States (or South Korea once operational control is transferred) is unlikely to agree to any Japanese plan to strike or counterstrike North Korea as that could increase the risk of friendly fire against U.S. or South Korean forces operating in the theater. Such an option would also be likely to cause problems for the existing preparations of the United States and South Korea, as well as for the agreed division of operational responsibilities between them: Japanese missile operations could, for example, disrupt plans related to when and where U.S. and South Korean forces should be at the onset of hostilities. While the solution would be trilateral collaboration in the U.S.-South Korean planning process to involve Japan, continuing sour ties between Tokyo and Seoul likely preclude such a solution for the foreseeable future.
The second scenario to consider is a conflict involving China, and that case would generate distinct challenges for the U.S.-Japanese alliance, with three issues being especially problematic.
First, China houses many of its nuclear capabilities alongside its conventional ones. Should Japan field weapons capable of reaching these missile sites, the Chinese government’s strategic calculations could be adversely affected. Although this may be a positive development from a deterrence standpoint, any contingency potentially involving nuclear weapons would prompt the involvement of U.S. Strategic Command and levels of classification that go well beyond what Japanese officials are likely privy to (as Tokyo does not possess strategic weapons of any type). American policymakers may be uncomfortable with Japanese operations that carry the prospect of strategic escalation but that have not been coordinated with U.S. planners in advance.
A second issue stems from China’s size. Because China is vastly larger than North Korea, Japan’s Self-Defense Forces would likely need help gathering operational intelligence as they work to build their own capabilities, including cyber, electronic warfare, long-range radars, sensors, and satellites. Pouring resources into these capabilities, assuming Japan’s overall defense budget is not greatly increased, would be likely to negatively affect Japan’s procurement efforts in other critical defense areas, possibly causing capability gaps elsewhere that might necessitate greater efforts from the United States.
Finally, unless fully planned for and framed within an alliance operational construct in advance, Japan and the United States may have difficulty achieving consensus on strike operation objectives. Would American officials be satisfied with Japan only striking specific tactical targets like individual launchers? Would Washington urge Tokyo to aim at more operational-level facilities and systems that enable China to conduct or sustain its war effort? Or would the United States want Japan to use its strike options to impair China’s broader East China Sea operational area to enable the United States to project forces deep into enemy territory? This, in turn, raises questions about differences between U.S. and Japanese decision-makers in their willingness to pursue high-value targets. Such issues may need to be discussed thoroughly and resolved in advance of any move by Japan to field ground-based, long-range strike capabilities. And such questions are not likely to be settled easily.
The Need for New and Expanded Alliance Discussions
Examining the potential consequences for the U.S.-Japanese alliance is not the same as evaluating whether Japan should acquire strike options or not. We are not making any argument for or against Japanese strike capabilities. Nor do the insights gleaned from the two scenarios offered above exhaust the possible consequences that Japanese procurement of ground-based strike options might have for the alliance. Other issues that may arise include matters related to doctrine and concept formation, training, command and control, intelligence sharing, operational coordination, posture, airspace deconfliction, and air and missile defenses. At the broadest level, there may be questions related to the nature of the alliance itself and whether it is shifting from its traditional shield-spear relationship to one more akin to two spears, albeit of different sizes.
Our objective is to emphasize that any Japanese acquisition of ground-based strike capabilities would have significant consequences for the U.S.-Japanese alliance and to highlight some of them. As the robust debates in Japan demonstrate, there may be deterrent advantages for the country should it field these capabilities. Yet if Japan does so, American and Japanese policymakers may need to have a new and expanded set of conversations about how such missiles will be used and how the alliance could adjust to incorporate them into this relationship.
Jeffrey W. Hornung and Scott W. Harold are senior political scientists at the nonprofit, nonpartisan RAND Corporation.