What’s Next for the U.S.-Japan Partnership?

The Donald Trump administration’s new National Security Strategy (NSS) makes very little mention of the alliance with Japan, other than calling for increased defense spending. If we want to foresee where the U.S.-Japan alliance is headed, we need to read the NSS in the context of relations under the new government in Japan.

Prime Minister Sanae Takaichi, a deeply conservative politician in the Shinzo Abe mold, rode a wave of nationalism and anti-foreigner sentiment in October to become Japan’s first woman prime minister. Takaichi currently enjoys immense domestic support—the Japan News Network opinion poll in November put her approval rating at 82 percent, the second-highest on record. But foreign policy poses important challenges for the new government as she is squeezed between a potentially unreliable ally and a more forceful China.

Although her summit with President Trump was widely hailed as a success in the Japanese media, it remains to be seen whether the United States’ commitments are credible. In addition, she was almost immediately embroiled in a conflict with China over Taiwan. Given the sharp cooling of relations with China and the formulation of the Trump administration’s America First policy in the NSS, Takaichi will pursue a “two-sword” policy: on one hand, “omotenashi,” meaning wholehearted hospitality toward the United States; on the other hand, she will continue the project of strengthening Japan’s own defense. This will include not only increased military spending but a possible revision of Japan’s “Three Non-Nuclear Principles.”

The Trump-Takaichi Summit

Trump and Takaichi had their first bilateral meeting on October 28, 2025, in Tokyo, one week after Takaichi took office. In the meeting, the two leaders declared a “New Golden Age” for the U.S.-Japan alliance, with Trump stating that Japan is “an ally at the strongest level.”

Takaichi is a protégé of former Prime Minister Shinzo Abe, a friend of President Trump who was shot and killed in July 2022, and she used this to her advantage to win the President’s trust—even gifting Trump with a golf club owned by his deceased friend. The Japanese media was ecstatic about the visit, remarking that Takaichi provided perfect omotenashi to the president. There were excited reports that President Trump introduced her as a “friend” when they visited the Yokosuka base, and that they watched a Dodgers World Series game together.

Beneath the love fest, however, are questions about the economic and security partnership. Many Japanese media fawned over the chemistry between the two leaders and seemed convinced that President Trump was recommitting to Japan’s defense. However, the summit received little media coverage in the United States, and some U.S. media suggested that President Trump, who met with Chinese President Xi Jinping just two days after meeting with Takaichi, was merely seeking to gain leverage over China by demonstrating strong political and economic ties with its allies. And as noted, the NSS devoted little space to Japan beyond a call for more defense spending and a passing reference to the Quad.

Rather, the White House has emphasized economic dimensions of the relations, including a framework agreement to secure the supply of rare earths and a trade agreement that included an enormous $550 billion investment from Japan in the United States.

Although the meeting was officially a success, it may be too early for Japan to conclude that it represents a long-term, credible commitment from the United States. As can be seen from how the summit was reported, there is a difference in enthusiasm toward the alliance between the two countries. It is worth noting that Trump also reached several economic agreements with Xi during their meeting in Korea, which he also called a great success. As long as it reaches economic deals with China, the Trump administration may see gains from provoking China through strengthening the alliance with Japan.

Rising China-Japan Tensions

Meanwhile, tensions between China and Japan are rising sharply. Takaichi, known for her hawkish stance on China, met with Xi for the first time on October 31, 2025, in a 30-minute meeting, during which they reaffirmed their commitment to building a stable relationship by pursuing common interests.

However, at the House of Representatives Budget Committee on November 7, Takaichi suggested that if China were to use force against Taiwan, it would pose an “existential risk” to Japan and that the Japanese Self-Defense Forces would respond militarily. As the Abe administration decided in 2014, the Japanese Self-Defense Forces can exercise the right of collective self-defense in a “survival-threatening situation.” Takaichi’s remark suggests a departure from the strategic ambiguity that Japan, as well as the United States, has maintained toward Taiwan under its One China policy for many years.

The remarks enraged China. The Chinese People’s Liberation Army took an unusual step of posting on X—in Japanese—that “if Japan dares to use military force to intervene in the Taiwan Strait, that will constitute an act of aggression, and China will strike back forcefully.” An outrageous post by the Chinese Consul General in Osaka that he will not hesitate to cut off that “filthy neck” that barges in without permission, sparked a fierce backlash both among Japan’s ruling and opposition parties. On November 15, China took a further step by advising its citizens to avoid traveling to Japan altogether.

Recent polls showed that over 50 percent of the Japanese public thought her remarks on the Taiwan Strait were appropriate, and her approval rating remains high. With strong domestic support, Takaichi may not repeat her claims about Taiwan, but neither is she likely to back down. Nevertheless, the United States’ response could be a disappointment to Japan. Instead of supporting her remark, Trump urged Takaichi not to rise to China’s provocation.

Prospects for Strengthening Japan’s Military Power

To address rapidly cooling relations with China and the uncertainty about the alliance’s credibility with the United States, the Takaichi administration is committed to accelerating the military buildup. This is evidenced by the rapid increase in defense spending to 2 percent of GDP two years ahead of the original schedule. A November opinion poll showed that more than 60 percent of the Japanese public, especially the young generation, supported the increase.

An interesting thing to watch is discussions on nuclear weapons. The Takaichi administration recently announced the potential revision of the “Three Non-Nuclear Principles.” Those principles include not possessing, not producing, and not allowing nuclear weapons to be brought into the country. Although Japan is part of the U.S. nuclear umbrella, the Non-Proliferation Treaty (NPT) has been the foundation of Japan’s postwar security policy. Given Japan’s ratification of the NPT, Takaichi clarified that Japan will maintain the first two principles, but that Japan may consider allowing U.S. nuclear weapons on Japanese soil. If this principle is revised, it will mark a major turning point for Japanese security.

Furthermore, a Japanese government official, who gives policy advice to the Prime Minister’s Office, recently made an off-the-record remark that Japan should possess nuclear weapons. It not only caused a huge backlash at home, but also a U.S. State Department spokesperson indirectly discouraged Japan’s nuclearization by praising Japan’s NPT.

However, Trump, who has even made statements encouraging Japan’s nuclearization based on the principle of self-defense, would likely welcome Japan’s policy direction, at least regarding the revision of the “not allowing” principle. Knowing that, Takaichi may see this revision in doctrine as a way to signal to the president her commitment to the alliance.

The Quest for a Mutually Beneficial Partnership

Despite uncertainties, the alliance with the United States is likely to remain essential for Japan. Takaichi will be expected to use her first “sword” to build a strong personal relationship with Trump by providing impeccable “omotenashi.” At the same time, she will use her second sword to continue to assert her own vision of self-defense. This includes both ongoing efforts to upgrade Japan’s defense capabilities while also using the revision of the three nuclear principles to signal resolve and solidify the alliance relationship. With the threat of China swirling, the new prime minister will exert this two-sword policy to achieve a mutually beneficial relationship with a United States singularly focused on America First.

Miki Hayashi is a PhD candidate in political science at UC Riverside and a 2025-26 IGCC Dissertation Fellow.

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