If China moves on Taiwan, Asia moves with it

China’s President Xi Jinping expects South Korea to make the “right strategic choices”. This is what he told South Korean counterpart Lee Jae-myung during their 5 January meeting in Beijing. But while his exhortation was officially a call for Seoul to work with Beijing to “oppose protectionism”, support “true multilateralism” and an “orderly multipolar order”, it also seems a veiled threat to avoid any interference in the event of a Taiwan crisis.

It is becoming evident that South Korea, whether its government agrees or not, would be part of the equation if the Chinese were to attack the democratically governed island, as is the case for Japan and the Philippines.

This is primarily due to the tyranny of geography. The United States Forces Korea (USFK), in addition to their efforts to prevent a North Korean invasion, would be taking steps to address a Taiwan contingency. General Xavier T. Brunson, the current USFK commander, reportedly said at a recent forum in Seoul that his units would adopt “strategic flexibility” on the issue, building on his previous observation that USFK could deter China’s Northern Theater Command by conducting actions in the waters off South Korea’s western coast.

During his visit to Seoul in November, US Secretary of War Pete Hegseth also made it clear that USFK could be used to deter a regional threat such as an emergency for Taiwan. The Lee administration is likely trembling at the idea, even though during a visit on 6 January to the South Korea-US Combined Forces Command, South Korean Defence Minister Ahn Gyu-back “called for a firm readiness posture in a changing security environment”.

In fact, South Korea has the potential to become a launch pad for US attacks on several fronts in Northeast Asia. USFK could pummel the northern flank of a Chinese amphibious force during invasion operations against Taipei. It could also target possible Sino-Russian activities to pin down Japanese forces in northern Japan, thus alleviating Chinese diversionary pressure on Tokyo as it tries to defend its southwestern islands close to Taiwan from a preventive blitz launched by Beijing.

Still, a combination of US, South Korean and Japanese naval and missile units could rush to block the entrance to the Yellow Sea and Bohai Gulf at the start of a crisis. This area is the gateway to the Beijing-Dalian-Qingdao triangle, which represents the geographical heart of China’s political and military strength.

In Brunson’s words, it looks like the Pentagon and US allies are working to create “overlapping dilemmas for adversaries” such as China along the first island chain, which encompasses Japan, Taiwan, the Philippines and Indonesia.

On top of the future USFK role, as observed by US strategist Dan Blumenthal, “Xi Jinping would have to preemptively attack Japan if he wanted a successful full scale invasion of Taiwan”. That is why the Chinese leadership has responded angrily to Japanese Prime Minister Sanae Takaichi’s comment that China’s aggression of Taiwan could constitute “an existential crisis” for Japan.

China cannot ignore Japan’s military buildup across the Ryukyu island chain, with the presence of missile systems, ammunition storage compounds and radar platforms. It is not by chance that during the recent large-scale military exercises around Taiwan, the Chinese deployed warships and drones close to Yonaguni Island, which lies approximately 110 kilometres from Taiwan’s northeast coast.

In the US strategic calculus, the Philippines must be another dilemma for China — part of the Pentagon’s attempt to create multiple attack axes against Chinese invading forces. US troops are actively operating in the northern section of the country, primarily in Luzon and Batanes. Their focus is on deterring China by controlling strategic waterways like the Bashi Channel near Taiwan. This involves the deployment of mobile units equipped with anti-ship missiles and drones to reinforce the first island chain defence.

It is worth noting that South Korea is a major arms supplier to Manila, providing key military hardware like modern frigates and FA-50 light fighter jets. These assets significantly bolster the Philippines’ naval and air power in the South China Sea, where it is locked in territorial disputes with China, as well as its capabilities in the Luzon Strait near Taiwan.

So if China is really willing to retake Taiwan by force, it must be ready to fight on four fronts at once.

Due to its nexus with the US, South Korea cannot escape this dynamic, which seriously weakens President Lee’s efforts to reset relations with China. Xi wants Seoul to “stand on the right side of history”, but the South Koreans will not join hands with Beijing in condemning Takaichi’s positions on possible Chinese invasion of Taiwan. Lee has been adamant in saying that his country will not meddle in the ongoing Sino-Japanese spat.

Not only that, South Korea is not in the position to prevent an expanded role for USFK, as the Trump administration could retaliate by putting into question the US commitment to deter North Korea or resuming tariff threats.

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