The global economic cost of a Taiwan Strait military conflict has been modeled by institutions ranging from the Rhodium Group to Bloomberg Economics to various government think tanks and war gaming centers. The estimates vary widely because the scenarios they model vary widely — a short, limited conflict produces different numbers than a prolonged blockade, which produces different numbers than a full-scale invasion with global power intervention. What the models agree on is that the numbers are very large, larger than any economic disruption since the Second World War, and large enough that they constitute an argument for prevention that is separate from any moral or political case for Taiwan’s defense.

Taiwan’s military has a personnel problem that its equipment purchases cannot solve. The active force — approximately 165,000 personnel across the Army, Navy, Air Force, and Marines — is designed for a conventional defense posture that the island’s strategic situation may not support. The reserve force, nominally numbering in the millions, is trained to a standard that multiple independent assessments have described as inadequate for the dispersed, mobile operations that Taiwan’s actual defense requirements would demand. The gap between the military on paper and the military that can fight is the most urgent operational readiness problem Taiwan faces, and it is one that requires sustained political will rather than procurement decisions to address.

The PLA Rocket Force — elevated to service branch status in 2015 from the former Second Artillery Corps — is the component of Chinese military power that most directly shapes Taiwan Strait risk assessments. Its inventory of conventional ballistic and cruise missiles, built over thirty years of investment that accelerated after the 1996 Taiwan Strait crisis demonstrated American carrier leverage, is the primary instrument through which China can threaten Taiwan’s military infrastructure, its population centers, and the American and allied forces that would respond to any attack. Understanding what the Rocket Force can do in the first hours of a conflict is prerequisite to understanding every other aspect of Taiwan Strait security.

Stretching from Kyushu southwestward toward Taiwan, the Ryukyu island chain forms a natural barrier between the East China Sea and the Philippine Sea. The chain includes Okinawa — site of the largest American military concentration in the western Pacific — and continues through progressively smaller islands to the Yaeyama group, whose southernmost point lies less than 75 miles from Taiwan’s northeastern tip. This geography is not coincidental to the Taiwan question. It is central to it. Any Chinese military operation in the Taiwan Strait must account for the Ryukyu chain, and any American or Japanese response to such an operation would use the chain as its primary operating framework.

The Senkaku Islands — known as the Diaoyu Islands in China — are eight uninhabited islands and rocks administered by Japan in the East China Sea, approximately 170 kilometers northeast of Taiwan and 330 kilometers west of Okinawa. Japan claims sovereignty. China claims sovereignty. Taiwan also claims sovereignty, though Taiwanese governments have generally handled the claim with less assertiveness than Beijing. The islands have no permanent population and no inherent economic value beyond the fisheries and potential hydrocarbon resources in the surrounding waters. Their strategic value lies entirely in their position: they sit at the junction of Japan’s Ryukyu chain and Taiwan’s northern approaches, and whoever controls them controls observation and potentially military positions that are relevant to both the East China Sea competition and the Taiwan Strait contingency.

Taiwan’s largest trading partner is the People’s Republic of China. By a significant margin. The two sides of a strait that are separated by competing political claims, opposing military forces, and seventy-five years of antagonism trade more with each other than Taiwan trades with the United States and Japan combined. This fact sits at the center of the Taiwan strategic problem in a way that military analysis consistently underweights: the economic integration that has developed between Taiwan and China since the 1990s has created dependencies that shape the behavior of Taiwanese businesses, the political calculations of Taiwanese voters, and the investment decisions of multinational companies with operations on both sides.

Vietnam fought China in 1979. The two-month border war, triggered by Vietnam’s invasion of Cambodia to remove the Chinese-backed Khmer Rouge government, cost tens of thousands of lives on both sides and ended without a clear military result. Vietnam held its positions. China withdrew. The war left a deep imprint on Vietnamese strategic culture: the understanding that China is a permanent neighbor with permanent interests in Vietnamese subordination, and that resistance — rather than accommodation — is the posture that Vietnamese sovereignty requires.

The Center for Strategic and International Studies published a major wargame analysis of the Taiwan Strait in January 2023. It ran 24 iterations of a Chinese invasion scenario, varying assumptions about Chinese military capability, American intervention, Japanese participation, and Taiwanese defense posture. The headline finding — that the United States and its allies could likely defeat a Chinese invasion but at very high cost — made international news. The details of the analysis were more nuanced and more alarming than the headline suggested. Understanding what the wargames actually show, and what they cannot show, is prerequisite to understanding the current state of Taiwan contingency planning.

The legal status of the Taiwan Strait has become an active diplomatic flashpoint rather than a settled background condition. The United States and its allies assert that the strait is an international waterway subject to the freedom of navigation that applies to straits used for international navigation. China asserts that the strait is Chinese internal waters, through which foreign military vessels do not have an automatic right of transit. These positions are irreconcilable, and the competition to establish which one is treated as authoritative by state behavior is a current, active dimension of the Taiwan Strait competition that operates below the threshold of military confrontation.

The question of when — not whether — China might attempt military action against Taiwan has become the organizing analytical question of western Pacific security. It is asked because Chinese leaders, most explicitly Xi Jinping, have provided a series of statements and deadlines that create at least a public framework for reading Chinese intentions. That framework is ambiguous enough that analysts reach different conclusions from the same data, which is itself informative: ambiguity about the timeline is probably a feature of Chinese strategy rather than a gap in its communication.