A piece missing from Australian conversations on the China–US tangle over Taiwan is the island’s growing strategic importance to other countries in the region. What happens between Beijing and Taipei matters for Japan and South Korea.

Things are moving fast in Northeast Asia. Seoul has long been reluctant to speak out about China’s claims over Taiwan or its expanding military exercises in the Taiwan Strait. Under President Moon Jae-in, South Korea was wary of offending China, its largest export market, and had its hands full countering North Korea’s nuclear and ballistic-missile programs without worrying unduly about Taiwan. It seemed inconceivable that Seoul would coordinate with Tokyo and Washington to oppose Chinese policy in the Taiwan Strait. And yet towards the end of his term, in May 2021, Moon issued a joint statement ^[1] with President Joe Biden emphasising ‘the importance of preserving peace and stability in the Taiwan Strait’. That was a small step for Washington but a big step for South Korea.

Then, at Camp David earlier this month, South Korea’s President Yoon Suk-yeol issued a joint statement ^[2] with Japan’s Prime Minister Fumio Kishida and Biden affirming ‘the importance of peace and stability across the Taiwan Strait as an indispensable element of security and prosperity in the international community’. Declaring stability in the strait a concern for the international community is what China calls ^[3] ‘internationalising’ the Taiwan issue, another no-no. This was hardly new for Yoon’s Japanese and American co-signatories, who issued a similar statement ^[4] at the close of the G7 meeting in Hiroshima in April, but for Seoul it was another big step.

Between times, Yoon mooted developing a nuclear deterrence force but opted instead to visit Washington and secure express commitments ^[5] from the American president on stationing nuclear weapons and on sharing sensitive information over North Korean missile activities. Another big step. Why?

The audacity and timing of Seoul’s comments point to a growing convergence between the tensions dividing China and Taiwan along the Taiwan Strait and those dividing the two Koreas at the 38th parallel. These two flashpoint fault lines are merging, geopolitically, around an unresolved and potentially explosive historical impasse concerning national division and reunification in Northeast Asia.

A fundamental principle of nationalism, understood as the everyday ideological underpinning of the international state system, is that nation-states should be whole, bounded and sovereign. A nation-state that regards itself as substantively incomplete, rightly or spuriously, is likely to be an unstable revisionist member of the international system. China is such a state, as are the two Koreas and post-Soviet Russia. Today these self-proclaimed incomplete states are concentrated in one volatile region, Northeast Asia, where irredentist sentiment can be heard clamouring on one side or the other for territorial unification.

Systemic instability of this kind need not portend conflict, but the likelihood of conflict rises and falls with other factors, including economic relations, ideological affinities, and relative military strength among revisionist and status quo states.

One factor is trade dependence. Claims of bilateral trade dependence on China are often overstated—as Australia discovered to its relief—but just 10 years ago dependence on China was very real in the case of Taiwan and South Korea. As value chains and supply chains move out of China, those claims are losing traction.

Taiwan’s policy options have long been thought constrained by its dependence on trade with China. True, China absorbs around 40% of Taiwan’s total exports, but final demand in China for Taiwan’s products is minimal. Jason Kao of the College of Management at Yuan Ze University in Taiwan estimates that 90% of Taiwan’s exports to China are processed for re-export from China for consumption elsewhere. If these value chains move out of China, Taiwanese firms are likely to follow them wherever they lead, taking the value with them. What’s more, says Kao, six of China’s top 10 exporting manufacturers are Taiwanese firms. If they were to leave, along with the value chains, it’s not Taiwan that would suffer but China.

Political and business leaders in South Korea appear to be drawing similar conclusions. Yoon’s decision to align with Japan and the US over Taiwan points to a major strategic reassessment by South Korea that its future is tied, not to China as it appeared a decade ago, but to an open global trading system governed by markets and the rule of law, with mobile value chains. As the China-dependence argument loses weight, its passing carries strategic implications as well as lessons for economic policy and businesses strategies.

This can’t be separated out from ideological differences. Ideological issues are gaining weight in political decision-making in the region’s key mover, China, as John Garnaut pointed out ^[6] more than six years ago. Ideological differences alone are unlikely to cause interstate conflict, but they hamper efforts to resolve it, the more so when they map directly onto divisions between states or alignments among them. In this case, geopolitical divisions separating each aggrieved state map closely onto their differences as either highly personalised dictatorships or constitutional democracies, and are reflected in evolving alignments among them, with the dictatorial states merging on one side and the democracies aligning on the other. It should be noted that none of the democracies proposes to invade or seize territory from its counterpart on the authoritarian side. Yet each faces a bullying neighbour that threatens to absorb or cut away at it.

A third factor is relative military strength, including nuclear capability. The most glaring difference separating the two aligned sets is that all three dictatorships are independently nuclear-armed while none of the democratic states they threaten possesses nuclear weapons. So the lessons that Sweden and Finland took from Russia’s invasion of Ukraine have not been lost on South Korea: whereas Stockholm and Helsinki scrambled for cover under NATO’s nuclear umbrella, Seoul doubled down on its commitment to US comprehensive deterrence.

And then there’s Japan. The region’s three incomplete revisionist states are not only nuclear-armed and aligned, but they share a deep hostility towards the other major non-nuclear democracy in the region, Japan. Taiwan and South Korea are on relatively good terms with each other and with Japan, giving Tokyo a stake in both converging issues, particularly the dispute between Beijing and Taipei.

In recent years, Japan’s leaders have declared peace and stability in the Taiwan Strait a matter of life and death for their country. On 8 August, former Japanese prime minister Taro Aso reaffirmed ^[7] his country’s commitment to non-nuclear principles, in a keynote address to the Taipei Ketagalan Forum, even when facing ‘the most severe and complex security environment since the end of World War II’. Echoing Kishida’s projection at the 2022 Shangri-La Dialogue—‘Ukraine today may be East Asia tomorrow’—he said Russia’s invasion of Ukraine showed that unilateral changes to the status quo could happen overnight and East Asia could be next in line. This matters for Taiwan, obviously, but it matters no less for Japan. Referencing the Hiroshima G7 statement, Aso said that peace and stability across the Taiwan Strait was an ‘indispensable element in security and prosperity in the international community’.

Aso’s message reinforced a statement ^[8] he made two years earlier that an invasion of Taiwan by China would pose a ‘threat to Japan’s survival’. He is not alone in this assessment. Few former leaders of Japan are quite as outspoken, but many concur with his assessment of the risks to Japan if a hostile government in Beijing were to take Taiwan. China would control commercial shipping in the Taiwan Strait, much as Russia now seeks to control cargo vessels in the Black Sea. That would threaten sea lanes vital to Japan and South Korea, and it could slice away the string of islands linking the main islands of Japan to the seas east of Taiwan, much as Russia is chipping off oblasts in eastern Ukraine. For Japan, as for South Korea, credible nuclear deterrence is a matter of national survival.

Only the US can provide that level of deterrence and, as the Hoover Institution’s Larry Diamond and James Ellis point ^[9] out, US credibility is on the line in Taiwan. Yoon went to Washington to secure further nuclear guarantees in the conviction, shared with his Japanese peers, that at this moment in history American comprehensive deterrence is essential for preventing the region from blowing itself apart.

Taiwan was not party to those conversations, nor was it invited to the Camp David summit, but with the growing convergence of interests among conventionally armed democracies facing nuclear-armed revisionist dictators, Taiwan can no longer be left out of consideration when Japan, South Korea and the US meet and act in the region. They each have good reason to care about Taiwan.