[Japan’s Voices No.13] How Should Japan Deal with Trump’s America?

In January 2026, the Trump administration released its National Defense Strategy. In its preface, Secretary of War Pete Hegseth dismissed the rules‑based international order as “cloud‑castle abstractions.” It is difficult to recall any recent U.S. administration defining the rule‑of‑law–based international order in such negative terms.

Although it has not made major headlines, this may well be the point at which Japan and the United States under the Trump administration diverge most sharply in their worldviews. For Japan, the principle that the status quo must not be changed unilaterally by force or coercion—and that international affairs must be governed by the rule of law—remains a central pillar of its diplomacy. 

Today, it is undeniable that the rules‑based international order faces an unprecedented crisis. This is not only because of Russia’s invasion of Ukraine or China’s coercive actions in the South China Sea and elsewhere, but also because the United States under the President Trump itself has turned away from the very principles it long championed.

When considering how Japan should deal with Trump’s America, the first question must be whether “Trump’s America” will persist indefinitely. The answer is: not necessarily.

To begin with, the 2028 presidential election looms large. Should President Trump’s low approval ratings persist, the Republican nominee—whoever that may be—will be forced to campaign under that burden and will likely face a tough battle. It is conceivable that the Republican candidate will have to run with Trump’s approval rating dipping below 40 percent. In 2008, Republican nominee John McCain ran while President George W. Bush’s approval rating had fallen below 30 percent and was defeated. The possibility of a Democratic return to power should not be underestimated.

Admittedly, the Democratic Party is far from unified, and no particularly compelling candidate has yet emerged. However, it is worth recalling that Jimmy Carter, Bill Clinton, and Barack Obama were all virtually unknown politicians several years before their elections. Moreover, in the 2024 presidential election, the nationwide popular‑vote margin was a mere 1.5 percent. In other words, the contemporary U.S. two‑party system remains intensely competitive. It is also possible that a non‑Trump challenger would emerge from the Republican Party.

In short, the outcome of the 2028 election will determine whether Trumpism endures or recedes.

However, even if a new Democratic administration sought to sweep away Trump‑era policies completely from the federal government, the task would be anything but easy. For instance, the conservative turn of the judiciary—where Trump appointed a large number of judges—will remain as a lasting legacy. Federal judges serve for life.

Of particular concern among Trump’s legacies is the polarization and degradation of American politics. In one respect, Trump did not create these problems single‑handedly. Ideological polarization has been intensifying since the 1990s, and the Trump phenomenon can be seen as a product of these accumulated trends, and it has further accelerated.

Ahead of the 2026 midterm elections, Texas Republicans aggressively redrew congressional districts to favor their party. Democrats responded by revising district maps in other states. Both parties, unabashedly pursuing partisan advantage, pushed redistricting to its limits. Such bare‑knuckled partisan combat will not simply vanish with a change in the Oval Office.

Even without being able to foresee 2028, Japan has more than sufficient reason to continue attaching great importance to today’s United States.

The second Trump administration intensified criticism of NATO allies and of Japan, South Korea, and other U.S. partners. The core argument was that allies had relied on American generosity while neglecting their own defense efforts, all the while enriching themselves with the wealth from the U.S. through unfair trade practices. Furthermore, toward Japan, Trump repeatedly hinted terminating the security treaty, arguing that its asymmetrical legal structure—Japan’s obligation being the provision of bases, and America’s obligation being Japan’s defense—was unfair because Japan bore no reciprocal duty to defend the United States. For European states facing a direct Russian threat since 2022, and for Japan facing mounting Chinese military pressure since around 2010, the situation is even more serious.

Japan’s foremost priority, needless to say, is its own security. Today, Japan cannot be certain it could fully defend even the territories it regards as its own. (The situations of the Northern Territories and Takeshima are regrettable, but Japan continues to pursue their return through diplomatic means in accordance with the rule‑of‑law principle.) North Korea’s nuclear and missile development, and above all, China’s growing military power and assertive behavior pose grave threats to Japan’s security. The military gap between China and Japan continues to widen. At present, strengthening Japan’s deterrence and response capabilities is essential to maintaining peace.

In this context, Japan has no choice but to prioritize retaining the United States—its sole treaty ally and the only power with military capabilities surpassing China. The joint statement reaffirming the alliance at the Japan–U.S. summit, and President Trump’s own declaration that the United States would defend Japan “100 percent,” including through nuclear deterrence (statement made after the Japan-U.S. Summit in February 2025), carry significant weight.

Equally important are members of the U.S. Congress. Unlike twenty years ago, today’s Congress is broadly critical of China and generally well‑disposed toward Japan. Numerous security experts in American think tanks also support the maintenance of the Japan–U.S. alliance. Japan has been the largest source of foreign direct investment into the United States for six consecutive years through 2024, surpassing the United Kingdom. Economic interdependence is deep, and cultural exchange is vibrant. Public opinion is also favorable: according to “US Poll on Opinions toward Japan” released by the Ministry of Foreign Affairs of Japan in April 2025, 77 % of the American public and 97 % of opinion leaders view Japan as a “trustworthy friend and ally.” There is no reason for Japan to distance itself from such a country.

While dealing with President Trump personally is primarily the responsibility of the Prime Minister and his/her Office, it is worthwhile for the government, the Ministry of Foreign Affairs, legislators, think tanks, and intellectuals to strengthen engagement with the United States at their respective levels.

At the same time, Japan must enhance self‑help and deepen cooperation with like‑minded or quasi‑allied partners. Japan is already strengthening its defense capabilities. Because Japan’s military posture is strictly defensive, it need not match an adversary’s capabilities symmetrically; depending on the scenario, possessing one‑third to one‑half of the attacker’s capability is said to provide effective deterrence by imposing sufficient costs.

Equally essential is expanding the number of states willing to support and act together to uphold the rules‑based international order. As an example, Japan and Australia have strengthened defense cooperation to the point of forming a “quasi‑alliance.” Japan is co‑developing next‑generation fighter aircraft with the United Kingdom and Italy. Joint exercises with France, Germany, and Canada are increasing. Japan’s defense support to the Philippines has progressed from radar provision to the supply of escort vessels. Japan enjoys strong trust with most NATO and EU members, grounded in shared support for the rule‑of‑law order. Effective cooperation among these states—many of which possess significant economic, military, and diplomatic weight—could exert considerable influence in international politics.

It is often said that today’s international environment resembles that of the 1930s. There is some truth to this, but what fundamentally distinguishes the present from the 1930s is precisely the existence and influence of these like‑minded states. Although America’s current posture under the Trump administration is ambiguous, Japan should encourage the United States to return to its traditional role. A full return may not be guaranteed, but the possibility is far from negligible.

People tend to become short‑sighted. Many in Japan may view Trump’s America negatively. Yet Japan must also consider America’s resilience and capacity for renewal. There is no need to idealize the United States; like all other nations, it is a troubled country with its own weaknesses and shortcomings. But like all other nations, it also possesses strengths worthy of recognition. At the same time, Japan must remain acutely aware of the security environment in which it now finds itself. 

Professor Fumiaki Kubo is a Senior Adjunct Fellow at the Japan Institute for International Affairs. He is also a former President of the National Defense Academy of Japan, a former President of the Japan Association for American Studies, and Professor Emeritus at the University of Tokyo.

The views expressed in this article are the author's and do not reflect those of JIIA CGO.