The United States and Japan’s vague, ahistorical version of the “one China” policy is inflaming tensions with Beijing.

The recent escalation of tensions between Japan and China has revived and intensified a perennial debate on the international legal status of Taiwan. Japanese prime minister Sanae Takaichi drew a vociferous response from Beijing when she said publicly in early November that a Chinese use of force against Taiwan could be deemed “a situation that threatens Japan’s survival,” implying that it might lead to Japanese military intervention.

The Chinese have since demanded that she retract her statements, insisting that the Taiwan issue is an internal Chinese affair in which no foreign country can interfere, and that Takaichi has violated prior Japanese acceptance of the idea that Taiwan is part of China. Chinese president Xi Jinping, in a subsequent conversation with President Donald Trump—no doubt aimed at getting Trump to press Takaichi to retreat—stated that “Taiwan’s return to China [after the defeat of Japan in World War II] is an integral part of the post-war international order.”

Understanding the context and significance of this episode and Xi’s statement requires a brief history lesson. Taiwan was incorporated into the Chinese empire in the 17th century, but the emperors paid it only episodic attention and usually had trouble exercising full control over it. It wasn’t until 1887 that Taiwan was designated a Chinese province.

Shortly thereafter, it was annexed and colonized by Japan following the Sino-Japanese War of 1894–95. While Taiwan was under Japanese control, the Chinese empire collapsed, and the “Republic of China” (ROC) was established in 1912. But mainland China then devolved into an intermittent civil war between the Nationalists (ROC) and the Communists, which was interrupted by World War II.

During the war, the United States was allied with the ROC against Japan. A crucial benchmark occurred in November 1943, when Franklin Roosevelt, Winston Churchill, and ROC leader Chiang Kai-shek issued the “Cairo Declaration,” which stated that “all the territories Japan has stolen from the Chinese”—including Taiwan—would be “restored to the Republic of China” after the war. This was reaffirmed by the same three leaders in the “Potsdam Declaration” of July 1945. And this is the basis for Xi Jinping’s statement to Trump that “Taiwan’s return to China” was integral to the post-war order.

But then the ground shifted. The Chinese Civil War resumed, and the Communists won, establishing the People’s Republic of China (PRC) in 1949. The Nationalists fled to Taiwan and maintained the ROC there as a rival Chinese government—still recognized by both the United States and Japan. And although Japan had been forced to renounce its claim to Taiwan, and the ROC had accepted the Japanese surrender of the island on behalf of the United States and its allies, sovereignty over Taiwan was never formally transferred to any power. When the Korean War broke out in 1950, President Truman declared that “The determination of the future status of [Taiwan] must await the restoration of security in the Pacific, a peace settlement with Japan, or consideration by the United Nations.” This was part of the basis for the view today that Taiwan’s status remains “undetermined.”

Returning to the present situation: proponents of Taiwan’s “undetermined” status rarely address the question of who or what will ultimately determine it and under what circumstances. As just noted, Truman in 1950 provided three options. “Security in the Pacific” arguably was restored with the Korean armistice, but that did not bring any formal adjudication of Taiwan’s status.

The peace treaty with Japan, signed in San Francisco in 1952, confirmed Tokyo’s surrender of sovereignty over Taiwan, but also did not formally transfer it to the ROC or any other entity—largely because the Chinese Civil War remained unresolved and other countries were working out how to deal with two rival Chinese governments (the ROC and the PRC). Interestingly, the failure of the treaty signatories—which included neither the Chinese regime—to assign sovereignty over Taiwan was driven as much by a lack of confidence in Chiang Kai-shek as by reluctance to undermine him by granting Taiwan to the PRC.

That left Truman’s option of “consideration by the UN,” which made a partial decision on Taiwan’s status in 1971 but did not fully resolve it. UN General Assembly Resolution 2758, entitled “Restoration of the Lawful Rights of the People’s Republic of China in the United Nations,” expelled the ROC from the UN and transferred its seat to the PRC. Although Beijing has insisted that this constituted UN recognition of Taiwan as part of China (and thus part of the PRC), the resolution included no such statement or ruling. Nonetheless, many supporters of Taiwan continue to believe (or hope) that the UN may yet play a role in determining Taiwan’s legal status by invoking the principle of self-determination as set out in the UN Charter—perhaps by arranging a plebiscite on Taiwan.

There are several obstacles to this, including Beijing’s veto in the UN Security Council and probably the unwillingness of many countries to antagonize the PRC by supporting such a plebiscite or any UN action on Taiwan that Beijing opposes. Perhaps more importantly, a majority of UN member countries support Beijing’s “one China principle,” according to which the PRC is the sole legal government representing China, of which Taiwan is “an inalienable part.” Moreover, a few UN member countries that do not fully subscribe to the “one China principle” appear willing to challenge it openly. Consequently, it is doubtful that the UN will play a role in determining Taiwan’s status in any way that Beijing opposes.

That brings us back to the question of who and what could “determine” Taiwan’s status, and to a particular dilemma that Washington and Tokyo face in the wake of Takaichi’s allusion to potential Japanese military intervention in Taiwan. Although both the United States and Japan reject Beijing’s “one China principle” and nominally subscribe to the notion that Taiwan’s status is “undetermined,” this is not consistent with their past historical positions.

When Tokyo normalized relations with the PRC in 1972, it affirmed that “The Government of Japan fully understands and respects” the PRC position “that Taiwan is an inalienable part of the territory” of the PRC. Although this is often loosely equated with the US statement (from when Washington normalized relations with Beijing in 1979) that the United States only “acknowledges” the PRC position, it originally meant more than that.

In an article published in 1973, a senior Japanese Foreign Ministry official clarified that “it is perfectly consistent with the past history as well as the [1952 San Francisco peace treaty] to take the position that Taiwan should be returned to China as intended by the Cairo and Potsdam Declarations. The Japanese Government…consequently has no objection to the island becoming part of the territory of the [PRC] and has no intention whatsoever to support the independence of Taiwan.”

The official added that the language in the Japan-China joint statement was “meant to reflect such [a] position.” Today, Tokyo resists offering any such clarity. In response to recent Chinese pressure, Takaichi has reaffirmed Japan’s adherence to the 1972 joint statement, but without further explanation. Beijing, however, deems this insufficient and is insisting that Tokyo provide clarification.

In the case of the United States, it is similarly clear that between 1945 and 1950, Washington never questioned the notion that Taiwan was part of China and that its “return to China” would be part of the post-war order (as per Xi’s recent statement to Trump). In January 1950, Truman—six months before declaring that Taiwan’s status would have to await further consideration—invoked the Cairo and Potsdam Declarations and included Taiwan within “Chinese territory.”

And although the US State Department later adopted the position that Taiwan’s status was left “undetermined” in the wake of the Korean War, its internal assessment of the origins of that position nonetheless suggests that the diplomatic players at the time all considered Taiwan to be Chinese territory.

Perhaps more importantly, President Nixon essentially abandoned the “undetermined” argument when he began the normalization process with the PRC. During his historic visit to China in 1972, he told Chinese premier Zhou Enlai: “There is one China, and Taiwan is a part of China. There will be no more statements made—if I can control our bureaucracy—to the effect that the status of Taiwan is undetermined.”

Accordingly, the joint communique that was issued publicly at the end of Nixon’s trip merely “acknowledged” Beijing’s position that Taiwan was part of China, but added that “The United States Government does not challenge that position.” Although subsequent US administrations have retreated from Nixon’s private statement to Zhou, Chinese leaders no doubt remember it and assign it historical weight. As a result, Washington’s position on Taiwan’s status—like Tokyo’s position—has a shaky historical foundation.

This is at the core of the controversy generated by Takaichi’s statement about a potential Japanese military response to a Chinese attack on Taiwan. It would be hard to avoid the assumption that such a Japanese response—presumably in support of US military intervention—would be driven by a determination to prevent Taiwan from becoming part of the PRC, arguably in violation of earlier US and Japanese commitments not to challenge the idea that Taiwan is part of China.

Some in Washington appear to believe that those commitments would be negated by a Chinese use of force, based on the erroneous view that Beijing, during the normalization process, committed itself to the peaceful resolution of the Taiwan issue. Beijing, in fact, promised only to “strive for” a peaceful settlement.

In effect, the preoccupation in Washington and Tokyo with a potential Chinese attack on Taiwan obfuscates (intentionally or otherwise) the erosion of the United States and Japanese “one China” policies. It also diverts attention from Taipei’s own retreat from a “one China” policy in favor of a de facto “one China, one Taiwan” policy—which, in Beijing’s view, the United States and Japan are tacitly accepting through their apparent acquiescence. Moreover, it diverts attention from Washington’s and Tokyo’s own drift toward de facto “one China, one Taiwan” policies, as reflected by their nascent preference for Taiwan’s long-term separation from China.

The latter arguably was hinted at in the Trump administration’s new National Security Strategy, which omitted any reference to a “one China” policy in favor of “our longstanding declaratory policy”—without defining it—and for the first time characterized Taiwan as a strategic linchpin, which was never a basis for Washington’s “one China” policy.

A Chinese attack on Taiwan would eclipse these trends in the United States and Japan—which have predictably fueled Beijing’s anger—and instead allow the United States and Japan to finger China as the source of escalating cross-Strait tensions. Indeed, Tokyo and Washington appear poised to intervene militarily in defense of Taiwan, its democracy, and regional stability—setting aside the inconsistency of their respective views on whether Taiwan is part of China and whether its status is “undetermined.” This would also bypass the question of whether Taipei itself is interested in any version of unification with China, and whether there is any version that Washington and Tokyo would encourage or pressure Taipei to accept.

The United States and Japan, however, need to have a clearly established position on Taiwan’s sovereignty that is not contingent on a Chinese use of force. Both Tokyo and Washington are evading this requirement by repeating vague and increasingly non-persuasive affirmations of their “one China’ policies and invoking the fig leaf that Taiwan’s status is undetermined, without addressing how it might be determined.

The preoccupation with the threat of a Chinese attack on Taiwan is neither facilitating a de-escalation of cross-Strait tensions nor enhancing Taiwan’s long-term security. One can readily be sympathetic to the people of Taiwan: their desire for self-determination, and their discomfort with the historical trap that they were caught in, first by Chiang Kai-shek and later by Beijing, Washington, and Tokyo. But Taiwan cannot escape its history any more easily than China, the United States, or Japan can escape theirs. And clinging to the theory that Taiwan’s status is “undetermined” offers little opportunity for resolution, given the historical weaknesses of the argument.

Washington and Tokyo should instead be confronting the dilemmas inherent in their “one China” policies and their own historical accountability. They should pursue a diplomatic approach to the Taiwan issue that is not focused exclusively on military deterrence. If dialogue over time among Washington, Beijing, Taipei, and Tokyo cannot find a way to clarify Taiwan’s status, great-power politics or military force will.

Source: National Interest, 16 December 2025… by Paul Heer