Japan is strongly invested in maintaining peace and stability on the Taiwan Strait, given how vital both mainland China and Taiwan are to Japan's economic interests. Japan would have a strong incentive to stay in step with the G7 in the case of heightened tensions, and despite some ambiguity, would likely have a significant role in any kinetic contingency. Japanese politicians have become more vocal advocates of Taiwan in recent times, but Tokyo is keeping the door open for dialogue with Beijing ahead of the fiftieth anniversary of restored diplomatic ties on 29 September.
Web of Interests
Japan’s response to the invasion of Ukraine has been robust, staying lockstep with G7 peers in implementing tough sanctions on Moscow and providing financial support and even (non-lethal) military aid to Kyiv. Tokyo wishes to project even an greater resolve towards Beijing to deter consideration of comparable events in the Taiwan Strait, but Japan faces a complex set of calculations in balancing relations with its most important economic partner and its most amicable democratic neighbor.
On one side, mainland China is Japan’s largest partner in goods trade, with two-way trade reaching around USD 300bn annually (almost 50% higher than the equivalent US-Japan figure); a major source of tech products, food, and clothing; and the destination for over USD 130bn in cumulative investment since the 1970s. On the other hand, Taiwan is Japan’s fourth-largest trading partner with bilateral goods trade in the region of USD 70bn per year; the predominant source of high-end semiconductors that are vital to Japan’s manufacturing industry; and the destination for around USD 50bn of cumulative FDI since the 1950s. The Taiwan Strait is also a vital artery for Japan’s broader global trade, including energy imports from the Middle East, and submarine cables around Taiwan are important conduits for its international communications.
Japan’s core position towards its former colony is like that of the United States in most respects. Since 1972, it recognizes Beijing rather than Taipei as the sole legal government of China but has not explicitly recognized Beijing’s sovereignty over Taiwan. It similarly seeks the maintenance of the status quo, does not endorse any moves for a Taiwanese declaration of independence, and advocates a peaceful resolution of issues through bilateral dialogue. It also is uncommitted to any specific course of action in a contingency, maintaining its own form of strategic ambiguity. But in contrast to the US, Japan does not have a law comparable to the Taiwan Relations Act and does not sell weapons to Taipei.
Hypotheticals
If tensions were to heighten considerably and the G7 imposed sanctions on China, Japan would have a strong incentive to keep in step as it has done regarding Russia. The economic disruption would be huge, but the alternative would be to fracture Western unity at a moment when Japan’s own territory (especially the Senkaku Islands) would be at risk of invasion. Japan’s response to any kinetic contingency would fall into one of three categories under the current legal framework.
In an “important influence” situation that would have a strong bearing on national security and could lead to a direct attack on Japan, the Self Defense Forces (SDF) could legally provide rear area logistical support for US forces deployed around Taiwan. A “survival-threatening” situation—an armed attack on a foreign country in a close relationship with Japan that would pose a clear risk to Japan’s survival—would seemingly allow for rear area logistical support if the US was operating solely in defense of Taiwan or collective self-defense if it were defending Japan. In an “armed attack” scenario where an attack on national territory had occurred or was imminent, the SDF would be authorized to act to its fullest capacities in concert with US forces, and the Civil Protection Act would be triggered to enable the evacuation of residents from outlying parts of Japan's southwest island chain.
All those situations are unprecedented and give rise to debate over how the government would respond in reality to various theoretical permutations. But since the terms of the alliance require Washington to get Tokyo’s permission before launching operations from Japan to third countries, it is highly likely that military bases in Okinawa and elsewhere would quickly become ensnared in any China-US engagement, escalating Japan to the third scenario. Perhaps a greater concern for Tokyo are practical issues such as the SDF’s ability to defend far-flung rocks like the Senkakus while simultaneously evacuating as many as 250,000 nationals from China, Taiwan, and Japan's own Sakishima Islands.
Balancing Act
Japanese leaders have become increasingly vocal about Taiwan in recent times, as they continue to ditch a long-standing policy of hedging between China and the US to become partisan advocates of the international rules-based order. Reportedly at Japan’s insistence, the Biden-Suga post-summit statement in April 2021 included the first mention of Taiwan in such a document since 1969. Japan’s 2021 defense white paper also introduced the issue of Taiwan, and the foreign ministry referred to Taipei as an “extremely important partner.” A series of remarks last year by then-deputy prime minister Taro Aso, then-defense minister Nobuo Kishi, and late former premier Shinzo Abe served as attempts to shift the interpretative framework for intermediate scenarios. Forums for dialogue between parliamentarians in Japan’s ruling LDP and Taipei counterparts have also strengthened in the last year or two, and two separate delegations of Japanese lawmakers visited Taipei this July and August.
Despite such outreach, Tokyo’s strong preference remains the maintenance of positive relations with Beijing. Even after five Chinese missiles landed in the waters of Japan’s exclusive economic zone (EEZ) during last month’s post-Pelosi live-fire drills, Foreign Minister Yoshimasa Hayashi made clear that the door remained open for dialogue with Beijing. Top foreign policy officials held a seven-hour meeting last month in Tianjin, and the forthcoming fiftieth anniversary on 29 September of the joint communiqué that restored diplomatic ties offers an opportunity for conciliatory gestures. A Kishida-Xi summit is once again being mooted, possibly to be held remotely or in a third country in November. With the recent scandal over the LDP’s links to the Unification Church causing the most damage to the party’s hawkish right wing, the more moderate Kishida now has greater space to pursue a much-needed détente.