A Japanese View from America | September 2026 | Pacific Research Institute | What If America Changes? What Should Japan Do? — The Kavanagh Report and the Next U.S.-Japan Alliance
By Tato Takahama
Pacific Research Institute
September 15, 2026
A new report on U.S. strategy in Asia deserves close attention in Japan.
Its title is A Second Island Chain Strategy for Asia, written by Jennifer Kavanagh, a political scientist who has spent much of her career examining U.S. military strategy, force posture, defense spending, and overseas intervention. She has worked at RAND and the Carnegie Endowment for International Peace and is now Senior Fellow and Director of Military Analysis at Defense Priorities, an organization that advocates “realism and restraint.”
Kavanagh’s proposal is striking. The United States, she argues, should shift the center of gravity of its military posture away from the First Island Chain, close to China’s coast, toward a Second Island Chain extending through Guam, Palau, Micronesia, the Marshall Islands, and Australia.
The underlying argument is that America’s forward military posture in Japan, Taiwan, South Korea, and the Philippines carries an increasing risk of war with China while imposing costs that may no longer be justified by U.S. interests.
For Japan, Kavanagh goes further. She proposes a substantial reduction of the U.S. military presence, initially bringing it down to roughly 5,000 personnel. Her longer-term proposal would reduce the U.S. presence in Japan to about 20,000 personnel by 2030 and 12,000 to 15,000 by 2035, with the eventual goal of eliminating permanent U.S. forces while retaining selected access points for rotational deployments.
If such a strategy were ever adopted, the question of the American nuclear umbrella over Japan would inevitably have to be reconsidered as well.
This is why the report matters.
I do not read Kavanagh’s proposal simply as a call for the United States to “get out of Japan.” The deeper question it poses is more uncomfortable:
What will Japan do if America changes?
There is no evidence that Kavanagh is a policy adviser to President Donald Trump. Indeed, she stands outside the Trump administration. Nor are Kavanagh’s views identical to Trump’s “America First” nationalism.
Yet there is an important area of overlap: skepticism about the extent to which the United States should indefinitely carry the security burden of other countries, reluctance toward open-ended military intervention, and pressure on allies to assume greater responsibility for their own defense.
The Kavanagh report therefore should not be treated as a secret blueprint for Trump. It is more useful to read it as an early expression of a debate that may continue in the United States even after Trump leaves office.
America’s fiscal constraints, competition with China, simultaneous strategic demands in Europe and the Indo-Pacific, and a domestic question that will not disappear—“Why should American taxpayers continue to bear so much of the cost of defending wealthy allies?”—will remain.
That is why I see the report as a warning about the post-Trump future.
There is an old way of thinking about great-power rivalry that may help explain the strategic logic. In the world of Japanese popular storytelling, figures such as Shimizu Jirocho were imagined as bosses with their own territories. Each had to calculate how far the neighboring boss would extend his reach and how far he himself should go. Rivalries could produce conflict, but they could also end in an accommodation.
The analogy is obviously imperfect. Relations between the United States and China are vastly more complex than a struggle between rival bosses. Yet the basic strategic question is comparable: how far will each great power project power, where will it draw limits, and where can the two avoid direct confrontation?
Kavanagh’s Second Island Chain strategy can be read in precisely these terms. Washington would step back from the First Island Chain while reinforcing the Second. It would seek to reduce the danger of a direct military confrontation with China close to the Chinese mainland without abandoning the Pacific altogether.
In other words, the United States would not necessarily be leaving Asia. It would be stepping back from China’s immediate doorstep.
For Japan, that distinction is critical.
Japan has become a principal platform for the U.S. strategy of deterring China. Okinawa illustrates the dilemma. The debate over American bases has long been framed primarily in political, historical, and emotional terms: pro-base or anti-base.
But the strategic environment has changed. China’s military capabilities have expanded, tensions around the Taiwan Strait have intensified, and the southwestern Japanese islands have acquired greater military significance.
Even if the U.S. military presence were eventually reduced, Okinawa’s strategic importance would not necessarily decline. If Japan assumes greater responsibility for its own defense, the importance of the southwestern islands could actually increase.
This brings us to the policies of the Takaichi government.
I believe the government is right about one fundamental point and potentially wrong about another.
Strengthening Japan’s defense capabilities is necessary. Whether American forces remain in Japan at their current level or eventually decline, Japan must be capable of defending itself. Long-range strike capabilities, air and missile defense, ammunition stockpiles, unmanned systems, space, cyber capabilities, and maritime and air power all matter.
But strengthening defense capabilities is not the same thing as permanently defining China as an enemy.
Japan must take China’s military expansion and its behavior in the East China Sea and around Taiwan seriously. Yet deterrence and hostility are not synonymous.
A stronger Japan can actually have greater room for diplomacy. A weak country may have little choice but to accommodate a stronger neighbor. A capable country can deter while maintaining dialogue.
Japan should therefore strengthen its defenses not simply to prepare for war with China, but to reduce the likelihood that war becomes necessary.
This leads to an issue Japan can no longer avoid: nuclear deterrence.
Japanese debate often collapses into a binary choice—nuclear weapons or the Three Non-Nuclear Principles. Once the argument is framed that way, meaningful discussion tends to stop.
Europe offers a different lesson.
As uncertainty grows over the long-term U.S. role in European security, European governments have begun examining how their own conventional forces, missile defenses, long-range strike capabilities, and nuclear deterrence might fit together.
France and Germany, in particular, have established a framework for deeper discussion of deterrence, including how French nuclear capabilities might contribute to broader European security. In March 2026, the two governments created a high-level nuclear steering group and agreed to German participation in French nuclear exercises.
This should not be described simplistically as the creation of a European version of NATO nuclear sharing. France has not transferred control over its nuclear weapons to its European partners. The French president retains sole authority over their use. NATO’s Nuclear Planning Group, meanwhile, remains the principal forum for consultation and decision-making on the Alliance’s nuclear deterrence, and France remains outside the NPG by choice.
What is emerging in Europe is something broader: a debate over how allies can participate in, support, and strengthen nuclear deterrence without necessarily acquiring nuclear weapons themselves. The debate has continued to evolve, with Finland joining France’s Forward Nuclear Deterrence Initiative on September 14, 2026. Finnish officials have stressed that the initiative complements rather than replaces NATO’s nuclear deterrence framework.
Japan should study this question seriously.
Researching nuclear sharing is not the same as acquiring nuclear weapons. Greater Japanese involvement in consultations concerning U.S. extended nuclear deterrence is not the same as developing an independent Japanese nuclear arsenal.
The relevant question is not simply whether Japan should “go nuclear.” It is how a non-nuclear Japan can contribute to, and derive greater security from, a credible deterrence architecture.
That leads to what I would call a “non-nuclear leverage” strategy.
A country does not need nuclear weapons to strengthen deterrence. It can combine long-range precision strike, air and missile defense, submarines, unmanned systems, space-based early warning, cyber capabilities, resilient command-and-control systems, dispersed bases, ammunition reserves, infrastructure protection, economic security, and intelligence-sharing with allies and partners.
None of these capabilities is nuclear.
Together, however, they can alter an adversary’s calculation by making aggression less likely to achieve its objectives.
Deterrence is not measured simply by the number of nuclear warheads.
It also depends on whether an attacker believes that its objectives can be achieved; whether the target can survive an initial strike; whether it can detect and respond to military moves; and whether aggression would trigger a broader coalition involving the United States, Australia, India, and European partners.
Japan should therefore broaden the nuclear debate.
The question should not be only, “Should Japan possess nuclear weapons?”
It should also be:
How can a non-nuclear Japan deter a nuclear-armed power?
That is a major psychological shift for postwar Japan.
It also points toward a broader transformation in Japanese diplomacy.
The U.S.-Japan alliance remains indispensable. But Japan should not allow its security strategy to rest on a single pillar.
Japan should deepen cooperation with Australia, India, Britain, France, South Korea, ASEAN, the European Union, the G7, and the Quad. It should develop overlapping networks rather than depend exclusively on any one bilateral relationship.
At the same time, Japan should maintain channels of communication with China.
Deterrence and dialogue are not opposites.
Japan can deter Chinese coercion while maintaining military hotlines, diplomatic exchanges, economic ties, people-to-people contacts, and other mechanisms designed to prevent a crisis from becoming a war.
A strong country is not simply one that can fight. It is one that has enough strength to negotiate without fear.
This is where the work of Amitav Acharya becomes relevant. In The End of American World Order, Acharya developed the concept of a “multiplex world”—a more decentralized and pluralistic international order in which multiple powers, institutions, and actors interact rather than operate under a single dominant order.
Japan needs a multiplex security strategy of its own.
The U.S.-Japan alliance should remain. But it should be supplemented by multiple security and diplomatic networks.
And Japan should reconsider the alliance itself—not abandon it, but make it more reciprocal and strategic.
Instead of asking only what America will do for Japan, Tokyo should ask what combination of American and Japanese interests can sustain the alliance.
If the U.S. military presence declines, what will Japan assume?
In return, what commitments will Washington make concerning extended nuclear deterrence?
How far should Japan become involved in a Taiwan contingency?
How clearly will the United States commit itself to Japan’s defense?
How deeply should Japan study nuclear sharing?
And if Japan remains non-nuclear, how far should it go in developing the conventional, technological, economic, and diplomatic capabilities necessary to compensate for the limits of nuclear deterrence?
These are not anti-American questions.
They are questions about the terms of the next U.S.-Japan alliance.
The Kavanagh report does not simply ask whether American forces will leave Japan.
It asks whether Japan is prepared to redesign its national strategy if America changes.
The Takaichi government’s defense buildup can be part of the answer. But it cannot be the whole answer.
Japan must think about nuclear deterrence without rushing to nuclear weapons. It must examine nuclear sharing without confusing it with nuclear acquisition. It must develop non-nuclear forms of deterrence. It must reconsider Okinawa, its relationship with China, and the structure of its alliance with the United States.
In the short term, Japan should strengthen its defense capabilities.
In the medium term, it should build a denser network of security and diplomatic partnerships.
In the long term, it should be prepared, if necessary, to renegotiate the terms of the alliance itself.
America may change. Trump may remain influential, or a future president may return to a more traditional alliance-centered policy.
Japan should not entrust its future to any single American president or to any single version of American strategy.
In the world of Shimizu Jirocho, rival bosses fought over territory and sometimes settled their disputes through accommodation. In the twenty-first-century Pacific, Japan cannot afford to spend its energy deciding which great power to follow.
It needs the capacity to defend its own territory—and the diplomatic strength to talk to those who challenge it.
That does not mean abandoning the United States.
Quite the opposite.
If Japan wants the U.S.-Japan alliance to remain indispensable, Japan must develop a strategy of its own.
That may ultimately be the most important lesson of the Kavanagh report.
Note: English translation was prepared by the author. Translation assistance tools may have been used.
2026 SEP | A Japanese View from America | PRI | アメリカが変わったとき、日本はどうするのか――カバナー報告書が突きつけた「次の日米同盟」
References
Jennifer Kavanagh, A Second Island Chain Strategy for Asia, Defense Priorities, September 10, 2026.
Emmanuel Macron and Friedrich Merz, “Joint Declaration of President Macron and Chancellor Merz,” Élysée Palace, March 2, 2026.
NATO, “Nuclear Planning Group,” updated May 20, 2026.
Amitav Acharya, The End of American World Order, Polity Press, 2014.
The views expressed in this post are solely those of the author and do not necessarily reflect the views of Cultural News.