The Japanese contribution to a Taiwan contingency was, until recently, an open question. Article 9 of the Japanese constitution prohibits the maintenance of war potential. The interpretation was strict for most of the postwar period and has loosened steadily since the early 2000s. The pace of loosening has accelerated in the last five years to a point where the formal constitutional position and the operational reality have diverged considerably. This is the most important development in the Western Pacific that does not get the attention it deserves.

Australia’s relationship with the Taiwan question is defined by a gap between its strategic reality and its public political language. The strategic reality is that Australia is a treaty ally of the United States, a member of the Five Eyes intelligence partnership, a signatory to AUKUS with its consequent nuclear submarine commitment, and a country whose trade relationships, geographic position, and alliance obligations make it impossible to remain neutral in a Taiwan Strait conflict that involves American military action. The public political language has been more cautious, with Australian leaders consistently declining to state explicitly what they would do in a Taiwan contingency, preferring instead formulations about supporting the peaceful resolution of the dispute and avoiding statements that could be read as provocation by Beijing.

India fought a border war with China in 1962, has had active military clashes with Chinese forces along the Line of Actual Control as recently as 2020, and maintains a territorial dispute with China that has never been formally resolved. It is a member of the Quad alongside the United States, Japan, and Australia. It has been deepening security cooperation with the United States, Japan, and Taiwan itself through informal technical and commercial channels. And yet India’s position on the Taiwan Strait remains studied ambiguity: it recognizes the People’s Republic of China, does not formally recognize Taiwan, and has consistently declined to make explicit statements about what it would do in a Taiwan contingency.

South Korea is an American treaty ally. It hosts 28,500 American troops, maintains one of the largest and most capable military forces in Asia, and has built its security architecture around the American alliance since the Korean War armistice of 1953. In any straightforward reading of alliance logic, Seoul should be a reliable partner in a Taiwan contingency. The reading is not straightforward. South Korea’s Taiwan position is defined by a set of structural constraints that make explicit commitment to Taiwan’s defense politically impossible in Korean domestic politics and strategically dangerous given Korea’s specific vulnerability profile.

The agreement reached between the United States and the Philippines in 2023, expanding American access to four additional Philippine military bases under the Enhanced Defense Cooperation Agreement, was one of the most strategically significant military basing decisions in the western Pacific since the 1991 closure of Clark Air Base and Subic Bay Naval Station. The locations matter more than the number. One of the four new sites is in Cagayan province on the northern tip of Luzon — the closest Philippine territory to Taiwan, roughly 200 miles from the southern end of the island. American forces with access to this location have a forward operating position that changes the geometry of any Taiwan contingency response.