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.”