Not Just an Island: Why Geography Should Not Drive U.S. Taiwan Policy

Geography always matters in international politics, as Iran has reminded us in the Strait of Hormuz. In the Western Pacific, Taiwan’s geographic status as an island 100 nautical miles off of mainland China is clearly important. After all, if Taiwan were a peninsula rather than an island, would we be discussing it today as anything but a fully integrated province of the People’s Republic of China (PRC)? It is undeniable that Taiwan’s island status has been a critical enabler of U.S. efforts to deter the PRC from attempting to forcibly absorb Taiwan. But Taiwan’s geographic position in Asia’s first island chain should not become the main reason why the United States supports Taiwan’s security. Emphasizing geographic interests in Taiwan in U.S. policy over other political and economic factors will do more to undermine what have been very successful U.S. deterrent efforts than to bolster them.

Preventing a PRC attack on Taiwan and the regional and global catastrophe it would cause should be the main focus of U.S. policy toward cross-strait relations. It should also be the foundation of Taiwan’s own defense strategy. But how the United States explains why deterrence of a PRC attack is vitally important to U.S. national interests has important implications for deterrence itself. Recently, senior U.S. officials, government strategy reports, and expert commentators have emphasized Taiwan’s strategic geographic location in the first island chain in the Western Pacific as the key reason why the United States should care about the island’s protection from hostile takeover by the PRC. Because Taiwan lies in the middle of the first island chain in the Western Pacific, control of the island by the PRC would, all things being equal, allow China to more easily project military power toward the second island chain and toward U.S. allies in the region. For example, Biden administration Assistant Secretary of Defense Ely Ratner suggested in Senate testimony that PRC control of Taiwan would gravely threaten the security of Japan and the Philippines: “Taiwan is located at a critical node within the first island chain, anchoring a network of U.S. allies and partners—stretching from the Japanese archipelago down to the Philippines and into the South China Sea—that is critical to the region’s security and critical to the defense of vital U.S. interests in the Indo-Pacific.” The Trump administration’s 2025 National Security Strategy Report similarly states that Taiwan’s security is of great concern “mostly because Taiwan provides direct access to the Second Island Chain and splits Northeast and Southeast Asia into two distinct theaters.”

This is the wrong justification for the right cause. Taiwan’s security is indeed critically important to U.S. security posture in East Asia, but its position in the first island chain is not nearly the most important reason why. A PRC attack on Taiwan would challenge the United States’ reputation in other Asian capitals as a resolute and effective ally. This would be true regardless of any newfound geographic advantages China might or might not enjoy by controlling Taiwan and stationing military forces there. Taiwan is also a fellow democracy and major U.S. economic partner worthy of assistance in deterring authoritarian takeover. Perhaps most important, a successful PRC military campaign against Taiwan would almost certainly have negative implications for future PRC attitudes toward its regional neighbors, some of whom are U.S. allies and several of whom have outstanding sovereignty disputes with China. What version of a future China the United States will be facing, and how confident it will be in its ability to solve regional problems by force, are much more important questions than the locations from which that China would be able to launch future military offensives.

Moreover, as Jonathan Caverley of the U.S. Naval War College has argued in rigorous detail, China’s military modernization will likely provide similar power projection capabilities against U.S. allies and partners and U.S. military assets in the Western Pacific even without PRC control of Taiwan. In other words, the delta of PRC control of Taiwan may not be very great once one fully considers preexisting trends in China’s power projection capabilities from territory it already controls on mainland Asia and at sea—on Hainan and Woody Islands, for instance. Caverley, however, hardly expresses indifference about Taiwan’s security. He recognizes that there are reputational and political reasons to want to prevent Beijing from settling cross-strait differences in its favor by the use of force; geography is just not high on his list.

Why The Geographic Argument is Problematic for U.S. Policy

Emphasizing Taiwan’s geographic importance over political factors related to Taiwan’s security unwittingly does more to undercut deterrence than to enhance it. A geographic focus logically calls into question key elements of the very successful U.S. “One China” policy. That policy toward cross-strait relations has helped produce a remarkable outcome: There has been no significant conflict in the Taiwan Strait since 1958. The U.S. policy is intentionally ambiguous on two important matters: (1) under what conditions the United States would intervene militarily to assist in Taiwan’s defense, and (2) the sovereign status of Taiwan in relation to mainland China, a status that remains undetermined in U.S. law. The central emphasis in U.S. policy toward relations across the Taiwan Strait has been on process, not on outcome. Any agreement reached peacefully between the two sides, including the people of Taiwan, would be acceptable to the United States. Until then, the United States remains opposed to destabilizing unilateral changes to the status quo by either side of the Taiwan Strait, meaning a use of force by China to compel unification against Taiwan’s will or political initiatives on Taiwan moving toward permanent legal independence from the Chinese nation without China’s consent.

This traditional U.S. policy posture allows domestic political room for China’s argument that peaceful unification across the Taiwan Strait is a future possibility. It thereby reduces the nationalist volume regarding the PRC’s need for military action to compel unification. It also reduces the likelihood of unnecessarily provocative political posturing by nationalist Taiwanese politicians who advocate permanent legal independence for Taiwan from the Chinese nation. Taiwan’s pro-independence voices grow louder when U.S. military intervention in Taiwan’s defense is seen as more certain. For both reasons, the U.S. “One China” policy as it currently stands has greatly reduced the likelihood that force would be used by the PRC against Taiwan. China’s use of force to achieve unification appears too risky and costly because of the quite real prospect of U.S. intervention to oppose compelled unification, and the use of force to prevent Taiwan’s permanent separation from mainland China is unnecessary because the United States opposes unilateral assertions of permanent Taiwan independence from the Chinese nation, thereby making that position much less attractive in Taiwan’s politics.

When U.S. officials and experts emphasize the importance of Taiwan’s geography, they are suggesting the need to deny the PRC’s control of Taiwan under all political circumstances. Such a posture undermines both stabilizing aspects of strategic ambiguity: Taiwan can never be permitted to be unified with the PRC, regardless of the process that produces such an outcome, and the U.S. commitment to the island’s defense would, logically, therefore be unconditional regardless of Taiwan’s political posture toward the PRC. To their credit and despite the positions cited above, neither the Biden nor Trump administration advocated abandonment of strategic ambiguity in favor of strategic clarity as a declaratory policy. But it is hard to come to any other conclusion about U.S. strategy if we accept the geographic premise regarding Taiwan’s importance to both the United States and the PRC. And it is no wonder that U.S. experts such as Richard Haass and David Sacks, who want to end strategic ambiguity in favor of an unconditional alliance-type commitment to Taiwan, begin by highlighting Taiwan’s geographic location in the first island chain as a major reason why: “If China were to gain control of Taiwan, it would have a much easier time projecting power in the Pacific Ocean and threatening U.S. territory, and the United States would struggle to defend its treaty allies, above all Japan and the Philippines, from Chinese aggression.”

Similarly unsurprising, officials in Taipei who want to tie the United States and its allies more tightly and less ambiguously to Taiwan’s defense have latched on to these U.S. arguments about the defense of the first island chain as a reason for both Washington and Tokyo to support Taiwan. Defense Minister Wellington Koo emphasized Taiwan’s “hub position” among countries in the first island chain. National Security Advisor Joseph Wu said that the PRC’s gray-zone activities near Taiwan threaten all countries in the first island chain. Foreign Minister Lin Chia-lung similarly asserted that “The first island chain should not be missing a single link, and Taiwan is precisely the critical link that has not yet been institutionally incorporated.” This strategy probably gained currency among Taiwan officials during the second term of the Trump administration because normal political appeals to the U.S. reputation as a security ally or partner, or the importance of the defense of democracy against authoritarian takeover, seem to resonate much less in U.S. politics during President Trump’s presidency than in the past.

Deterrence of a cross-strait conflict should be the goal for both the United States and Taiwan. An unconditional U.S. commitment to Taiwan’s protection from mainland control delegitimizes advocacy of “peaceful unification” in PRC policy circles, to the benefit of advocates for a more hawkish strategy toward both Taiwan and the United States. And under present conditions of strategic ambiguity, China already fully anticipates U.S. intervention in a cross-strait conflict if it were to attack Taiwan to compel unification, so clarifying the U.S. commitment by focusing on geographic imperatives is unnecessary to bolster the threat China perceives regarding the dangers of using force. But because it implies an unconditional support for Taiwan’s defense, the geographic focus on Taiwan’s importance does increase the likelihood that politicians and the public in Taiwan would take greater risks to assert permanent legal separation from the Chinese nation, and thereby spark an otherwise avoidable conflict. Public opinion on Taiwan regarding the island’s posture toward the mainland are greatly impacted by the respondents’ degree of certainty of U.S. military intervention in case of any ensuing conflict. And most experts on China’s security policy agree with this author that formal expressions of permanent separation from the Chinese nation by Taiwan’s leaders could trigger a cross-strait conflict regardless of the intensity of the U.S. commitment to the island’s defense.

Taiwan’s Geography in Historical Context

The valuation of Taiwan in geographic terms has a controversial history. In May 1950, General Douglas MacArthur labeled Taiwan an “unsinkable aircraft carrier and submarine tender.” Along with interagency allies at the Pentagon and State Department, he was trying to convince the Truman administration to make a clear, unconditional commitment to Taiwan’s security. Later that year, and after the outbreak of the Korean War, MacArthur criticized those who rejected such a clear commitment: “Nothing could be more fallacious than the threadbare argument by those who advocate appeasement and defeatism in the Pacific that if we defend Formosa [Taiwan] we alienate continental Asia.” MacArthur underscored the need to maintain control of what has been subsequently labeled the first island chain from “the Aleutians to the Marianas,” including Taiwan due to its central location in that chain. President Truman tried first to silence General MacArthur’s public expressions on policy issues that differed from U.S. strategy and eventually fired him for insubordination in 1951.

Even when the United States and Taiwan were formal allies from 1954–79, Taiwan’s geographic position in the first island chain was not the central reason for the United States to deter PRC attacks on the island. Political factors, including general opposition to communist expansion and the importance of the U.S. reputation as an ally, were at the center of U.S. Taiwan policy—not a need to prevent the PRC from occupying the island based on its geographic position. Taiwan’s democratization in the 1980s and 1990s added yet another compelling political reason for the United States to help Taiwan avoid takeover by an authoritarian mainland China.

Following the transfer of U.S. diplomatic recognition from Taipei to Beijing in 1979, the official U.S.-Taiwan alliance was dissolved. But Taiwan’s defense against forced unification remained important to the United States as was outlined in the 1979 Taiwan Relations Act (TRA) and the 1982 Six Assurances. The TRA is a law that calls for arms sales of a defensive nature to Taiwan and the maintenance of a strong U.S. military posture in the region should the president decide to intervene in a cross-strait conflict. The Six Assurances, which were originally classified, were a guarantee to Congress and to Taiwan by the executive branch that the United States would not negotiate away U.S. support for Taiwan’s security in diplomacy with China. These documents are essential elements of what has been a successful deterrent policy of strategic ambiguity toward Taiwan, in which the United States expresses its opposition to any unilateral changes to the status quo across the Taiwan Strait by either side.

Strategic ambiguity is not an unconditional U.S. alliance commitment to Taiwan’s security. Creating such strategic clarity would be both unnecessary and unwise because of the potentially negative political impacts on both sides of the Taiwan Strait. Highlighting Taiwan’s strategic geographic location over other important reasons to support its defense logically leads to the conclusion that the United States is dedicated to the permanent separation of Taiwan from China under all political circumstances. Such a posture is more likely to undermine deterrence than to bolster it by stoking conflicting nationalist political narratives on both sides of the strait that make war much more likely, not less so.

Thomas J. Christensen is Pritzker Chair in the Geopolitics and Foreign Policy Department at the Center for Strategic and International Studies in Washington, D.C. and James T. Shotwell professor of international relations and director of the China and the World Program at Columbia University’s School of International and Public Affairs.