The Western Pacific “island chains” are a persistent feature of Asia’s maritime geography. While their underlying fundaments remain constant, their specific strategic importance has evolved over time. Different major powers have thus interpreted, then re-interpreted and re-evaluated, the value of particular islands, the role they play in national military strategy, and their operational significance in a warfighting context. Chinese naval strategists such as former naval commander Admiral Liu Huaqing have devoted considerable attention to the island chains since the mid-1980s, examining how and where the island chains can hinder or support China’s maritime goals. Yet Chinese strategists are hardly unique in their efforts—military theorists and planners from Germany, Japan and the United States have all pondered the geopolitics of the islands and archipelagos of the Western Pacific, during both peacetime and wartime. To understand the progression of Chinese views, and more recent debates among U.S., Japanese and Chinese strategists, we must trace this lineage of strategic ideas that stretches back more than a century.
Foreign Imperial Origins
The earliest known inklings of island chain-related concepts are intertwined with imperial Germany’s Pacific involvement at the turn of the twentieth century, just as the United States was taking possession of Spain’s previous colonial Pacific territories of Guam and the Philippines. Germany’s tenure as a Pacific colonial power—having acquired the Mariana Islands; and the Caroline Islands, including Palau; from Spain in the aftermath of the Spanish-American War of 1898—coincided with the early writing career of Major General Karl Ernst Haushofer. Serving as a military attaché to Japan from 1908 to 1910, Haushofer was preoccupied with the geopolitics of the Pacific, penning several books on the subject. He regarded the “offshore island arcs” of what he termed the “Indo-Pacific realm” as important geopolitical features providing a useful “protective veil” sheltering continental powers such as China and India.
Japan, for its part, was already a major Pacific sea power at the turn of the twentieth century, having defeated the Chinese Navy and seized Taiwan in 1895. As its maritime strength increased, Tokyo gave careful attention to the strategic value of different islands and archipelagos in the Western Pacific. During World War I, a Japanese expeditionary force wrested control over several Micronesian islands from imperial Germany. These were not only useful stepping stones in Japan’s “southward turn,” focused on exploiting Southeast Asia’s economic and natural resources, but also served as a valuable strategic buffer. In particular, control over Micronesia (chiefly the Mariana, Marshall, and Caroline islands; the last, notably, including Palau) was seen as a hedge against the possibility that the United States would use its bases in Guam and on the Philippines to threaten Japan in a future conflict.
U.S. military theorist Milan Vego explains how Japan took steps to solidify its control over Micronesian islands in the decades following World War I. Vego observes that the Japanese government embarked on a significant settlement and economic campaign during the 1920s and 1930s. The number of Japanese settlers on the islands eventually outnumbered the native islanders. In 1935, Vego notes, Japan withdrew from the League of Nations and its islands became “closed territories,” with Westerners restricted from entry.
At the outset of World War II, the Imperial Japanese Navy engaged in a series of lightning-fast island seizure operations, landings, and fortifications. This included operations to seize both Guam and Wake Island from the United States. During the middle of the war, Japanese forces sought control over other islands within the Second and Third Island Chains, including the Solomon Islands and as far as the Aleutian Islands off the coast of Alaska. Although many islands formerly in Japanese possession passed to the United States the Soviet Union as a result of the war, Japan eventually regained control over key components of the First and Second island chains, including the Ryukyu and the Ogasawara islands.
Japanese concerns over U.S. island possessions in the Western Pacific following the Spanish-American War were mirrored by evolving U.S. concerns over Japanese control over parts of the island chains. As early as 1910-11, U.S. Navy military theorists, including scholars at the Naval War College, suspected that Japan might one day threaten American possession of the Philippines and Guam. The result was the so-called War Plan Orange, assembled by Rear Admiral Raymond Rodgers. This plan, first drafted in 1911 and refined over the next twenty-five years, anticipated later Pacific operations during World War II, including a “leapfrog” campaign to seize the Marshall and Caroline islands from imperial Japan.
The U.S. Marine Corps (USMC)’s contribution to War Plan Orange has been credited largely to Lieutenant Colonel Earl Hancock “Pete” Ellis, one of its intelligence officers, who distinguished himself as an early theorist of amphibious operations. Ellis contributed most directly through his development of Operational Plan 712, “Advanced Base Operations in Micronesia,” approved as a secret “War Plan” in 1921 by his mentor USMC Commandant Major General John Archer Lejeune. In it, Ellis foresaw the island hopping campaigns of two decades later and offered detailed plans for their successful prosecution by U.S. forces. Today, the USMC maintains that “the actual American campaign for Micronesia diverged from Ellis’ plan only in areas affected by technological advances.”
Ellis’s perspicacity may seem extraordinary, and was only fully recognized in hindsight—in part because of his death in 1923 from alcoholic complications in Palau, one of the Japanese-occupied Caroline Islands which he was attempting to survey covertly. But the strength of his conclusions clearly stems from their grounding in then-unprecedentedly-systematic analysis of the island chains’ geography and potential strategic utility. Ellis devoted particular attention to “the continued occupation of the Marshall, Caroline, and Pelew [Palau] Islands by the Japanese,” which “invests them with a series of emergency bases flanking any line of communications across the Pacific throughout distance of 2300 miles.” Describing these features as “a veritable ‘Cloud’ of islands and reefs” containing “chains of low coral stalls,” he offered what for his era was an exhaustive review of their geomorphology and its implications for the operations that he believed would be necessary to wrest them from Japanese control. To this end, he offered a detailed, hierarchical strategy for American seizure of these “inter-supporting island groups” and establishment of “base facilities for the further pursuance of our operations in areas beyond.” Ellis prioritized in particular the recapturing of Guam, “which it is expected will be strongly held by the enemy as a base.”
During the Pacific War, as Ellis foresaw, the U.S. military itself had to hold the island chains it already controlled, and to penetrate fortified Japanese-held island chains. Admiral Earnest King, for instance, believed that controlling Taiwan “would let the U.S. Navy ‘put the cork in the bottle’ of the South China Sea during World War II, severing Japanese SLOCs and thus Japan’s supply of oil and raw materials.” As Vego’s map below indicates, this American exploitation of theater geometry quite literally shaped the outcome of that epic transoceanic struggle.
Emerging victorious from the Pacific War, U.S. strategists soon turned their attention to the importance of the island chains in the nascent Cold War. It was in this period that the “island chains” concept itself was developed and defined clearly. Washington’s postwar Pacific strategy yielded the earliest explicit mention of an island chains concept we have found: a 1948 Joint Chiefs of Staff study demarcating an American defensive perimeter running from the Aleutian Islands, south through occupied Japan, then through Taiwan and the Philippines.
General Douglas MacArthur played a key role in thinking through the geopolitical significance of the island chains during the early Cold War. As Naval War College scholar Toshi Yoshihara points out, MacArthur argued that the U.S. military should establish a “striking force” stationed along a “U-shaped area embracing the Aleutians, Midway, the former Japanese mandated islands, Clark air base in the Philippines, and above all, Okinawa.” In his “Message on Formosa” of 17 August 1950, MacArthur described Taiwan as “an unsinkable aircraft carrier and submarine tender ideally located to accomplish offensive strategy and at the same time checkmate defensive or counter-offensive operations by friendly forces based on Okinawa and the Philippines.” In his 1951 farewell address to Congress, MacArthur distilled his island chain thinking into its most comprehensive and forceful essence, using it as a unifying theme to inform his final policy recommendations concerning the future of American strategy vis-à-vis the Asia-Pacific. In doing so, he described the U.S. Pacific posture as being quite literally based on the central outward-projecting angle of a bastion-battle line:
“. . . the western strategic frontier of the United States lay on the littoral line of the Americas with an exposed island salient extending out through Hawaii, Midway and Guam to the Philippines. That salient proved not an outpost of strength but an avenue of weakness along which the enemy could and did attack. The Pacific was a potential area of advance for any predatory force intent upon striking at the bordering land areas.
“All this was changed by our Pacific victory, our strategic frontier then shifted to embrace the entire Pacific Ocean which became a vast moat to protect us as long as we hold it. Indeed, it acts as a protective shield for all of the Americas and all free lands of the Pacific Ocean area. We control it to the shores of Asia by a chain of islands extending in an arc from the Aleutians to the Mariannas held by us and our free allies.
“From this island chain we can dominate with sea and air power every Asiatic port from Vladivostok to Singapore and prevent any hostile movement into the Pacific. . . .
“The holding of this defense line in the western Pacific is entirely dependent upon holding all segments thereof, for any major breach of that line by an unfriendly power would render vulnerable to determined attack every other major segment. This is a military estimate as to which I have yet to find a military leader who will take exception. For that reason I have strongly recommended in the past as a matter of military urgency that under no circumstances must Formosa fall under Communist control. Such an eventuality would at once threaten the freedom of the Philippines and the loss of Japan, and might well force our western frontier back to the coasts of California, Oregon and Washington.”
However ill-advised some of MacArthur’s actions in Korea and elsewhere; and however excessively-Taiwan-centric, exaggerated, or otherwise unrealistic the above maritime domino theory might be to implement fully in practice; his island chain philosophy indeed encapsulates some important strategic thinking of the era. Such thinking unquestionably influenced Chinese strategists as they sought to make sense of their nation’s geostrategic position, the security challenges it faced, and what it might do to address them.
China’s Appropriation of the Concept
In formulating their own views on the island chains, Chinese military theorists frequently look back on American strategic ideas from the mid-twentieth century. Many Chinese sources refer to early Cold War-era statements articulating the need for a U.S. defensive perimeter in the Western Pacific, such as that proposed by MacArthur and others, including Dean Acheson and John Foster Dulles. Tracing the origin of the concept, one Chinese military scholar states: “The term ‘island chain’ originated from the proposal made by Western countries led by the United States after World War II by taking advantage of the strategic geographic locations of some special island groups in the Northwest Pacific Ocean waters to suppress and block socialist countries at the time, such as the Soviet Union and China.”
Contemporary Chinese strategic thinking related to the island chains emphasizes the early Cold War-era U.S. strategy of constructing a defensive perimeter meant to contain the Soviet Union and its Chinese ally. As we chronicle in a recent China Quarterly article, Chinese military writings frequently refer to the island chains as barriers imposed by the United States that limit China’s ability to evolve into a genuine maritime power with freedom of maneuver throughout the Western Pacific. A 2007 article in the Chinese navy’s official magazine, for instance, declares that the island chains have the power to “contain China and the Chinese navy.” Two Chinese naval strategists similarly argue that the “partially sealed-off nature of China’s maritime region has clearly brought negative effects on China’s maritime security.” Moreover, harkening back to American activities in the 1950s, contemporary Chinese writings often portray U.S. force deployments in areas such as Guam, the Philippines, and Okinawa as the result of “Cold War thinking” designed to contain China.
A similar strand of Chinese military thinking conceives of the island chains as “springboards” from which the U.S. military can conduct operations close to Chinese sovereignty claims. For instance, retired PLAN Rear Admiral Zhang Zhaozhong has identified Guam as a strategic location from which the United States can “immediately send out aircraft or dispatch submarines, in order to put power into the war zone,” referring to the Taiwan Strait.
In contrast to these views of the island chains as the locus of threats posed by the U.S. military, some Chinese military theorists see the island chains more as benchmarks for Chinese military operations. This mode of thinking is most prominent among naval strategists. Admiral Liu Huaqing argued that, for the foreseeable future, most naval operations would be confined to the First Island Chain, which he defined as including Japan, South Korea, Taiwan, the Philippine Islands and the Greater Sunda Islands. But, as a long-term goal, Liu argued that China must be prepared to eventually operate out to the Second Island Chain, including the Mariana Islands, Guam and Palau. Chinese media frequently details progress towards this goal, describing in almost heroic terms the voyages of successive Chinese naval flotillas through the strategic passageways of the First Island Chain, and into more distant waters. For some, then, the island chains have become markers in China’s attempts to develop a “blue water” navy capable of performing both wartime and peacetime missions.
The Island Chains’ Enduring Relevance
Beyond the exigencies of specific planning scenarios, why do strategists from so many nations periodically fix their gaze—explicitly or implicitly—on the island chains? They do so because these long strings of land features have intrinsic geostrategic value. There is a basic geo-operational reason for this. Military platforms and their crews generally require support from appropriately-positioned terrestrial bases for their high-performance, sustained, cost-effective operation. As any glance at a globe reveals, the Pacific Ocean is vast, containing 714 million cubic kilometers of water, 50.1 percent of global seawater. It covers 165.25 million square kilometers (63.8 million square miles)—significantly more than the Earth’s total landmass of 150 million square kilometers (58 million square miles); and equivalent 46 percent of Earth’s water surface and one-third its total surface area. The rapidity and intensity of modern military operations place an additional premium on overcoming this “Tyranny of Distance” expeditiously. Basing military assets in-region, or at least enabling and supporting their deployment there, offers an unrivaled solution.
Yet the Pacific’s unparalleled expanse contains relatively few specks of land, widely dispersed. In the entire Pacific Ocean—including the home islands of Japan, the Philippines, and New Zealand; as well as Taiwan, Hainan, Papua New Guinea, and Hawaii—there are only 20 islands larger than 10,000 square kilometers (3,861 square miles). In the South Pacific (excluding Papua New Guinea), home to the majority of the ocean’s islands, the total landmass is only 551,913 square kilometers (213,095 square miles).
These factors put an inherent premium on the military value of any given Pacific feature, particularly the very few of sufficient size, resources, and human capital to host an advanced military facility. Hence, the late nineteenth century preoccupation with “coaling stations” to power the increasingly-long-range operations of the U.S. and other navies; the Imperial Japanese efforts to gain control of Pacific islands, both to enjoy their use and deny it to the United States; the protracted island hopping campaigns of the Pacific War; and the extraordinarily-rapid, -dramatic American transformation of re-captured islands such as Guam into major militarily facilities, at a cost possibly prohibitive in conditions short of world war.
To be sure, the island chains’ precise strategic value, and hence strategists’ specific emphases on them, has varied significantly as a function of changes in military technology and application—including what weapons are based on them, how far those weapons can reach, and whether it is possible to defend and supply them. This value changed significantly during the interwar period. It shifted profoundly during the Pacific War (which, among other things, highlighted the need for air defenses to protect ships and land installations and the importance of submarines in severing supply lines). Today, it is shifting greatly once more, with the advent of much longer-range strike systems (aircraft, anti-ship cruise missiles/ASCMs, land-attack cruise missiles/LACMs, conventional ballistic missiles); and defensive systems (long-range surface-to-air missiles/SAMs). These developments are dramatically increasing the range of shore-based systems versus those based on ships—a dynamic that Chinese planners have exploited deftly and systematically. This might also apply to the value of individual islands like Taiwan, which is not placed to expand China’s power projection capability significantly, but (by virtue of geography) could in theory offer a potent “springboard” for a foreign military to attack mainland China. Such theory might have accorded with empirical reality in 1980, but this is certainly much less the case today given the PLA’s ability to crater runways; attack command and control with precision strike weapons; and use long-range SAMs to attack aircraft as soon as they are airborne. In short, given today’s Chinese weapons, Taiwan is too close to mainland China to have maximum “strategic value.”
Island chains are the subject of focus as much for their exceptional vulnerability as for their exceptional capabilities, however. Their very concentration offers an enemy a conveniently-circumscribed target set. In today’s era of long-range precision strike (LRPS), the problem has become nothing short of acute. Not for nothing has China developed and deployed the world’s largest, most diverse sub-strategic conventional ballistic missile force. Beijing now has the ability to strike more islands, in more ways, more effectively; Washington and its allies must think how best to respond.
At the geopolitical level, as documented earlier, the island chains, like the region they shape geophysically, have long been regarded as important fulcrums of world affairs. Today, as the U.S. Pacific Command emphasizes,
“The 36 nations comprising the Asia-Pacific region are home to more than 50% of the world’s population…several of the world’s largest militaries, and five nations allied with the U.S. through mutual defense treaties. Two of the three largest economies are located in the Asia-Pacific. . . . The [region] includes the most populous nation in the world, the largest democracy, and the largest Muslim-majority nation. . . . The region is a vital driver of the global economy and includes the world’s busiest international sea lanes and nine of the ten largest ports. The Asia-Pacific is also a heavily militarized region, with seven of the world’s ten largest standing militaries and five of the world’s declared nuclear nations. Given these conditions, the strategic complexity facing the region is unique.”
The island chains have long been considered particularly relevant to opposing an authoritarian continental state’s attempt to dominate Eurasia, a central imperative of U.S. strategy since its ascendance to the world stage since the late nineteenth century. During the Pacific War, Tokyo—with its sweeping seizure of Chinese territory—arguably constituted precisely such a challenge. Throughout much of the Cold War, Washington mounted geopolitically-similar opposition to both Chinese and Soviet efforts to dominate Eurasia. Recently, with China’s rise and Russia’s military resurgence, at least some Western strategists perceive analogous dynamics.
In sum, in the geopolitically-vital Pacific, the relatively few desirable and available islands are disproportionately valuable for their ability to host vital military facilities. Despite their limited strategic depth and consequent growing vulnerability to LRPS weapons, they remain irreplaceable. After all, their number remains fixed—with one notable exception.
A New Island Chain?
Arguably the most interesting Pacific geostrategic development in recent years has been what might be broadly interpreted as China’s creation of a small new island chain in the South China Sea. While other neighboring coastal states have in previous years very slowly and modestly used land reclamation to augment features under their control, since 2014 Beijing has utterly surpassed them all, both qualitatively and quantitatively. China has engaged in industrial-scale dredging, reclamation, and construction to transform a set of seven Spratly submerged reefs and rocks into large artificial islands hosting a growing constellation of facilities, many militarily-relevant. Additionally, in the Paracels near Vietnam, China has further augmented features it holds, including the already-substantial Woody Island. Now, Woody Island in the Paracels and Fiery Cross and Subi Reefs in the Spratlys boast 3 km-long-runways, sufficient to accommodate all Chinese military aircraft. Mischief Reef, also in the Spratlys, has an airfield under construction that is nearly as long.
This represents an extremely rare case in history of a nation altering inconvenient facts of geography in its favor; previous Chinese geoengineering achievements included the Great Wall and the Grand Canal. Now, in the South China Sea, Beijing is literally raising from the depths a small inner island chain to outflank what it sees as foreign threats to its sovereign claims, in part from enemy forces able to utilize bases along the First Island Chain. This is the classic approach of a continental power operating along interior lines attempting to outmaneuver a maritime power operating along exterior lines—only in this instance, uniquely, projected far out to sea from artificial features. This configuration underscores a critical reality of China as a sea power: it has genuine maritime dynamism in ways that the Soviet Union and other land powers lacked, yet the core of its focus remains rooted in outstanding territorial claims within its immediate region. As such, it is poised to remain for the foreseeable future what might be termed a “land-sea hybrid” (陆海兼备) state that is developing tremendous scale and capabilities as a “maritime power” (海洋强国), while retaining a vital landward dimension as well. Given this geostrategic context, Chinese strategists will continue to place the island chains at the center of their thinking.
A Return to the Island Chains
Meanwhile, recent Chinese developments are returning foreign attention to the island chains. In the context of growing Chinese military capabilities and the perception of increasing Chinese assertiveness in the Western Pacific, Japanese and American strategists are once again thinking through the potential strategic and operational value of the island chains. Japan’s 2010 National Defense Planning Guidance articulated a “dynamic defense force” concept that places greater emphasis on air and ballistic missile defense in its southwestern islands. More recently, citing Japanese military officials, Reuters reports that Tokyo is responding to perceived Chinese threats by reinforcing islands between mainland Japan and Taiwan with anti-ship and anti-aircraft missile batteries. This is intended as “Joint Dynamic Defense,” a Japanese version of China’s “anti-access/area-denial” strategy designed to deter Chinese aggression within the First Island Chain. According to Satoshi Morimoto, a former Japanese defense minister, “In the next five or six years, the first island chain will be crucial in the military balance between China and the U.S.-Japan [alliance].”
Some U.S. military strategists are also reevaluating the importance of the island chains in light of China’s military development. In 2012 U.S. National Defense University scholar T.X. Hammes published a paper that based a military strategy on defending the First Island Chain, denying China’s use of the waters inside it, and dominating the waters outside it. In a 2014 monograph published by the Center for a New American Security, the Naval War College’s Toshi Yoshihara recommended a strengthening of defenses along the First Island Chain to support the U.S.-Japan alliance. In Yoshihara’s words, “the prospects of an impenetrable island chain would play on China’s nightmare scenario that the PLAN could be shut out of the most direct routes to the high seas, lending Japan a psychological edge.” In a 2015 Foreign Affairs article, Andrew Krepinevich of the Center for Strategic and Budgetary Assessments likewise proposes strengthening the First Island Chain in order to “deny Beijing the ability to achieve its revisionist aims through aggression or coercion.”
Chinese military strategists have already begun to think through the implications of such suggestions by some in the United States and Japan. Senior Colonel Liang Fang, an expert at China’s National Defense University, acknowledged in an interview with the PLA Daily that a “blocked island chain” could indeed have an effect on the ability of Chinese naval ships to “break through” the island chain. Nevertheless, in a more optimistic vein, Liang insisted that a shifting military balance in China’s favor would render such Japanese ambitions increasingly “delusional.”
Senior Colonel Liang’s observation raises a larger recurrent question, which is how changes in military technology, and especially the advent of LRPS capabilities, may affect the strategic value of particular islands and archipelagos. The U.S. Department of Defense’s 2015 report on Chinese military power notes that Taiwan’s defense capabilities have been “eroded” by China’s deployment of more than 1,200 ballistic missiles and other assets, such as improved submarines and combat aircraft. In this context, it is doubtful that Taiwan could serve as what MacArthur envisioned as an “unsinkable aircraft carrier” ideally suited for offensive operations against mainland China.
Beijing’s advances in longer-range ballistic and cruise missile technology also pose significant dangers to more distant islands, such as the U.S. strategic hub of Guam. This has, in turn, led scholars at RAND and elsewhere to explore concepts such as deception and dispersal that can be used to defend air bases across the Asia-Pacific from potential Chinese threats.
In the coming years, it is likely that Chinese, American and Japanese strategists—in addition to those from other maritime Asian states—will give concurrent attention to the role that the island chains can play in achieving national military objectives. Chinese strategists will increasingly focus on perceived vulnerabilities of U.S. and allied forces along the island chains, while the latter will consider how forces can be dispersed and hardened so as to deter Chinese aggression. Such strategic and operational calculations will be only the latest in a long line of thinking stretching back to the early twentieth century. How that thinking evolves could leave an indelible mark on the strategic balance in the twenty-first century.
Andrew S. Erickson, Professor of Strategy in the China Maritime Studies Institute at the Naval War College, blogs at www.andrewerickson.com. Joel Wuthnow is a Research Fellow in the Center for the Study of Chinese Military Affairs at the National Defense University. The views expressed are their own and do not reflect the official policy or position of the Department of Defense or the U.S. government. They thank Phillip C. Saunders and T.X. Hammes for valuable suggestions.
Image: Wikimedia Commons/U.S. Air Force photo by Senior Airman Carlin Leslie.