After last week’s decision to suspend deployment of Aegis Ashore missile defense systems — which is looking more like cancellation each day — Prime Minister Shinzo Abe said that Japan needs to discuss ways to strengthen its deterrence.

What he means — or more precisely, what he wants — is not yet clear, but he is right to call for a conversation on ways to strengthen Japan’s national defense. The security environment continues to evolve and Japan must think creatively about how it can address new threats and challenges.

Japanese security planning occurs within two inter-related frames: the domestic political context and the alliance with the United States. In the first, Japanese decision-making is constrained by Article 9 of the Constitution and an understanding that defense spending will not exceed 1 percent of GDP.

Abe chafes against both: Revision of Article 9 is one of his most cherished political objectives and he has said that he will ignore the 1 percent spending limit if national defense requires additional funds; defense budgets during his tenure have observed that ceiling, nevertheless.

Both constraints are reinforced by a profound skepticism of the military among the public. Many, if not most, Japanese fear entanglement in foreign conflicts if their country’s defense capabilities are enhanced or strictures on their use loosened. One of the most powerful manifestations of this mindset is the “not in my backyard” (NIMBY) phenomenon that has blocked virtually every new defense construction project in Japan, including the Aegis Ashore deployments.

Still, threats to Japan are mounting. North Korea, the most immediate concern, has steadily grown more capable and formidable; Abe warned that Pyongyang’s missile technology, which prompted the need for the Aegis Ashore systems, “has advanced since the time we introduced our missile defense systems.”

China is ever more ominous, too: It is a revisionist power, ambitious, aggrieved and eager to right perceived historical wrongs. One expression of that intention is evident in the East China Sea, where Chinese vessels daily enter the contiguous zone surrounding the Senkaku Islands, challenging Japan’s claim to administrative control of the territory. Japan must be ready for more forceful efforts to reassert China’s territorial claim.

Abe and some other politicians and strategists argue that one way Japan can better deter adversaries is by developing and deploying a preemptive strike capability — the ability to attack an enemy with missiles before it strikes. It is an appealing concept — passivity in the face of a visible and growing danger is difficult to sustain — but interest in it has waxed and waned depending on the state of that threat and the political strength of the government.

A Liberal Democratic Party panel endorsed the idea in 2017 after a worrying series of missile tests, but the breakthrough in relations between North Korea and the United States seemed to undercut the urgency of such a step. In the wake of the Aegis Ashore decision, acquisition of offensive capabilities is again rising to the top of the agenda as Abe worries about the emergence of a security vacuum.

There are numerous problems with that approach, however. It is expensive and difficult, requiring not only missiles but also intelligence collection capabilities so that Japan can identify threats in real time, track them down and hit them, a tough assignment when missiles are easily hidden and increasingly mobile.

In addition, decision-makers in Tokyo must figure out not only what their adversaries are doing but be confident as well in what they are thinking: Are weapons being moved to prepare them for use or to avoid being a target? Offensive capabilities can inflame crises as decision-makers adopt a “use it or lose it” mentality.

In the Japanese case, there are also legal issues: Some scholars argue that Article 9, which has been interpreted to limit Japan’s military to strictly defensive means, bans “strike” capabilities because they are “offensive” in nature.” The prevailing interpretation, however, is that the Constitution is not a suicide pact and the government can use such weapons if an adversary has started preparations for a missile attack on Japan, a position that is consistent with international law.

In deterrence, the key is complicating an adversary’s calculations. A weapons system doesn’t have to be foolproof. Rather, it only has to make an adversary doubt whether it can accomplish its objective. Ken Jimbo, a Keio University professor and one of Japan’s best strategic thinkers, thinks the strike option can do that, but only in combination with defense capabilities — and if Japan integrates its defense more closely with that of the U.S.

Jimbo identifies three rationales for “strike”: neutralizing an adversary’s arsenal in advance, which is virtually impossible given the size of North Korea’s missile inventory and inhospitable terrain that allows Pyongyang to hide those weapons; punishing an adversary after an attack, which requires Japan to have a huge arsenal of its own (again unlikely); or damage limitation, by which Japan could degrade an enemy’s threat before it strikes and then use defenses to defeat the surviving missiles. He concludes that “given Japan’s defense policy and budgetary constraints, the only viable option is the third idea.”

U.S. strategists concur. Brad Roberts, deputy assistant secretary of defense for nuclear policy and missile defense in the Obama administration, agrees that missile defenses aren’t a complete solution to the missile threat, as they can be overwhelmed by an enemy willing to fire large numbers in a massive attack.

“Counter-attack capabilities contribute to deterrence as well, including so-called left-of-launch capabilities that seek to disrupt attack by preemptive action, whether kinetic or non-kinetic,” he says. Roberts concludes that the Japan-U.S. alliance “needs an appropriate mix of defensive and offensive capabilities to meet the missile threat. That mix should include more and better Japanese strike assets.”

Which brings us to the second frame for Japanese security planning: the Japan-U.S. alliance. Japan cannot do this alone. Even if Japan acquires some missiles, it will rely on U.S. intelligence for targeting and the vastly larger and more powerful U.S. missile arsenal to “punish” adversaries. While Abe was right to say that “peace isn’t something someone gives to you,” to think that this portends an independent Japanese deterrent is mistaken.

Once, the U.S. was the pre-eminent military power that could (and had to) “extend” deterrence to its allies. That “golden age” of military superiority has passed and strategists and military planners in Washington and Tokyo (and Seoul and Canberra, and other allied capitals) must rethink what is required to ensure that adversaries are deterred. It is time to reassess foundational principles of defense and security, appreciate and incorporate a new premium on cooperation and coordination and recalibrate burdens and responsibilities, roles and missions.

It has been seven years since Japan issued its first National Security Strategy; it is time for an update. This will likely necessitate new National Defense Program Guidelines and a new Mid-Term Defense Program. The latter two documents must, however, be formulated in concert with the evolution of the Japan-U.S. alliance.

Significantly, rethinking deterrence demands a re-conceptualization that goes well beyond the traditional military framework. Not only must planners incorporate new domains — space and cyber — but they must be more creative in their use of the entire spectrum of military operations — from peace to wartime and the “gray zones” in between — and in utilizing other dimensions of national power that define the competition between states in the 21st century.


Brad Glosserman is deputy director of and visiting professor at the Center for Rule Making Strategies at Tama University as well as senior adviser (nonresident) at Pacific Forum. He is the author of "Peak Japan: The End of Great Ambitions."

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