One of the most urgent questions in international geopolitics today is which of the regions currently embroiled in conflict could eventually trigger a third world war – a war that, unlike its predecessors, would almost certainly involve, at the very least, the limited use of nuclear weapons. 

While the conflicts in Ukraine and Iran are potential flashpoints, the tensions in the Indo-Pacific are even more volatile. But while considerable attention has been paid to the threat of a Chinese invasion of Taiwan, analysts have arguably overlooked a more immediate danger facing the Ryukyu Island chain, the arc of 55 volcanic islands and reefs stretching northeast from Taiwan to Japan’s main island of Kyushu.

The risks in the Indo-Pacific are driven primarily by Chinese leader Xi Jinping’s long-held aim of reestablishing China’s perceived maritime hegemony over its littoral waters, including not only Taiwan but also the South and East China Seas. However, while China continues to threaten Taiwanese sovereignty, it is not pressed for time. Beijing has several ways of achieving its aims over the island, and not all of them military.  

First, China is assiduously courting Taiwan’s primary opposition party – the Kuomintang (KMT) – currently the largest party in Taipei’s Legislative Yuan. The KMT’s leader, Cheng Li-wun, recently visited Nanjing on the mainland, ostensibly to visit the mausoleum of Sun Yat-sen, the revolutionary leader that both Taipei and Beijing revere. Cheng also met with Xi in Beijing’s Great Hall of the People. Although there was considerable opposition to her trip in Taipei, the message to Taiwanese President Lai Ching-te was clear: there is a strong political alternative to your pro-independence ruling party that, if elected, could defer to Beijing’s wishes without necessarily submitting to direct rule.

Second, as the current conflict around the Strait of Hormuz vividly demonstrates, China recognizes that there are many waterways around Taiwan it could occupy, from the Taiwan Strait itself to the lesser travelled Luzon Strait. Limiting ship traffic in these areas would have a dire effect on Taiwan’s trade economy. Given the might of the People’s Liberation Army Navy (PLAN), the largest in the world by number of hulls in service, the task would not be onerous for Beijing. China could even look further afield, at the Straits of Malacca, for example, though a move on this front would likely be self-defeating. Malacca is also the transit point for a significant portion of China’s seaborne oil imports.

A third, more extreme option would be to blockade Taiwan by sea and air. The immediate consequences of isolating the island in this way could be catastrophic for Taipei, damaging its supply chain chip customers around the world.

While these potential courses of action relate to Taiwan, by far the most notable of Xi’s other objectives is to reclaim the Ryukyu Island chain, an archipelago that separates the relatively shallow waters of the East China Sea from the abyssal depths of the Western Pacific. Until 1874, when the islands were annexed by Japan, the Ryukyus formed a kingdom whose nominal fealty lay with China. Perhaps more significantly, the chain of islands represents an impediment to the covert transit of Chinese submarines from the PLAN’s main bases at Hainan Island and Qingdao, out into the open ocean and up to the limits of the Second Island Chain. Their existence also enables the Japanese military to monitor Chinese surface formations in the region, including the powerful PLAN carrier battle groups.

Seizing and occupying all of these islands and reefs would be impractical and costly for the PLAN; all but a handful are extremely remote and of limited military value. The main arc of the Ryukyus that extends northeast from the tip of Taiwan, including the Senkaku, Yonaguni, Miyako, Ishigaki, Okinawa and Amami islands, would on the other hand be a far more tempting target for Beijing’s naval and air forces.

For several years, China’s growing aircraft carrier fleet has been aggressively patrolling the waters surrounding Taiwan, as well as the maritime zones around the Ryukyu Island chain. As of writing, it totals three operational conventional carriers, with one nuclear powered vessel under construction. This last Type 004 carrier is estimated to displace in excess of 100,000 tons. Once launched, it will incorporate technology rendering it the equal of the latest U.S. Gerald Ford-class carriers.

When we consider the force that China could muster for an attack on the Ryukyu Islands, including its PLAN submarine and surface fleet and its formidable air force, targeting Yonaguni Island seems not only feasible but deeply attractive for China. Part of its decision to move hangs on the outcomes of the current conflicts in Ukraine and Iran, though, as both Xi and the Central Military Commission watch patiently while those wars grind on.

Recognizing the potential threat, the Japanese government and military are also preparing for potential hostilities in their southern waters. Since the beginning of the 21st century, Tokyo has been quietly equipping its armed forces to operate in something more than a “defensive mode.” It has built new major capital ships, albeit not at the frenetic pace of China. Given the vicissitudes of the current U.S. administration, and the uncertainty regarding American support for Japan in the event of a full-scale maritime conflict, Japan’s recently elected Prime Minister Takaichi Sanae won’t want to take any chances. 

Given all this, an escalation of hostilities between China and Japan over the Ryukyu Island chain seems worryingly likely. It may already be a question of when and not if.