The Historical Significance of Islands

Islands have been pivotal in shaping maritime strategy for millennia. Ancient city-states such as Rhodes and Carthage recognized that controlling nearby islands provided naval basing, protected harbors, and a commanding position over sea lanes. The Roman Empire leveraged islands like Sicily and Crete to project power across the Mediterranean, turning them into logistical hubs for grain shipments and military fleets. In the medieval era, the Republic of Venice fortified its island holdings along Adriatic trade routes, ensuring dominance in commerce and defense against Ottoman expansion.

The age of sail amplified the strategic value of islands. European colonial powers seized islands as coaling stations and resupply points for their far-flung navies. For instance, Britain’s control of Gibraltar, Malta, and Singapore—all islands or peninsulas—enabled the Royal Navy to enforce its maritime hegemony well into the 20th century. These historical patterns continue to resonate. Modern navies still rely on island bases to project power, protect shipping lanes, and secure exclusive economic zones (EEZs). Understanding this historical arc is essential for analyzing contemporary disputes over the South China Sea, the Arctic, and the Indian Ocean.

Strategic Chokepoints and Island Chains

Islands often sit adjacent to critical maritime chokepoints—narrow straits or passages where shipping traffic concentrates. These chokepoints are vulnerable to disruption, and the islands nearby become strategic prizes. The Strait of Malacca, for example, is flanked by Indonesia’s Riau Islands and Malaysia’s coastal islets. Control over these islands allows a nation to monitor or blockade one of the world’s busiest trade corridors, through which roughly 30% of global seaborne petroleum passes.

In the broader Pacific, the concept of “island chains” has become central to U.S. and allied defense planning. The First Island Chain extends from the Japanese archipelago through the Ryukyu Islands (including Okinawa), Taiwan, the Philippines, and down to the Malay Archipelago. This chain serves as a forward defense line, hosting key military installations and early warning systems. China’s maritime strategy explicitly aims to break out of this chain into the deep blue waters of the Pacific, leading to tensions over island sovereignty in the East and South China Seas. Similarly, the Second Island Chain (running roughly from the Bonin Islands through Guam to the Marianas) provides a fallback defensive perimeter and power projection for the United States. For more on chokepoint vulnerabilities, see the Council on Foreign Relations analysis of the Strait of Malacca.

The modern significance of islands is deeply embedded in international maritime law, particularly the United Nations Convention on the Law of the Sea (UNCLOS). Under UNCLOS, an island (defined as a naturally formed area of land, surrounded by water, above high tide) generates a territorial sea of 12 nautical miles, a contiguous zone of 24 miles, and an exclusive economic zone (EEZ) extending up to 200 nautical miles. This EEZ grants the coastal state sovereign rights over all natural resources—including fish, oil, and gas—within that vast area. Even a small, uninhabited island can thus claim an enormous expanse of ocean, making sovereignty disputes highly contentious.

The status of “rocks” versus “islands” under Article 121 of UNCLOS is particularly disputed. Rocks that cannot sustain human habitation or economic life of their own are entitled only to a territorial sea, not an EEZ. This distinction lies at the heart of many conflicts, such as those over the Spratly Islands, the Senkaku/Diaoyu Islands, and Dokdo/Takeshima. China’s construction of artificial islands and military installations in the South China Sea has further complicated interpretation, as built-up features do not automatically qualify as natural islands under UNCLOS. The full text of UNCLOS provides the foundational legal framework that nations invoke to support their claims.

Case Studies of Islands in Maritime Strategy

The Falkland Islands

The Falkland Islands (Malvinas) remain one of the most vivid examples of island-driven military conflict. Located roughly 300 miles east of the Argentine coast, these remote British Overseas Territories hosted a small population and strategic embayment for naval operations. In 1982, Argentina’s invasion triggered the Falklands War, a major combined-arms campaign that the United Kingdom ultimately won after deploying a naval task force across 8,000 miles of ocean. The conflict demonstrated that even small islands could trigger a major power projection contest, and that air superiority from island bases—like the Royal Air Force’s use of Ascension Island as a mid-Atlantic staging point—was decisive. Today, the UK maintains a garrison and modernized air defenses, while Argentina continues its diplomatic claim. The islands also sit above potentially significant offshore oil deposits, adding an economic dimension to their strategic value.

The Spratly Islands

The Spratly archipelago comprises more than 600 islets, reefs, and atolls spread across the South China Sea. Claimed in whole or in part by China, Vietnam, the Philippines, Malaysia, Brunei, and Taiwan, these features are strategically located near critical shipping lanes that carry about $3 trillion in annual trade. China has militarized several features—building airstrips, radar systems, and missile batteries on artificial islands—despite a 2016 Permanent Court of Arbitration ruling that such actions violate UNCLOS. The Spratlys sit atop geologically promising sedimentary basins containing oil and natural gas, and fisheries that sustain millions of livelihoods. The ongoing standoffs between Chinese and Philippine vessels at Second Thomas Shoal highlight the flashpoint nature of these remote islands. For a detailed breakdown of competing claims, see the Asia Maritime Transparency Initiative’s map and analysis.

Guam

Guam, the southernmost of the Mariana Islands, has been a linchpin of U.S. Pacific strategy since World War II. Its deep-water port at Apra Harbor and Andersen Air Force Base provide forward-deployed capabilities for bombers, submarines, and amphibious forces. The U.S. is currently investing billions to harden Guam against missile threats, constructing new air defense systems and bunkers. As tensions over Taiwan and the South China Sea escalate, Guam is increasingly seen as a critical “unsinkable aircraft carrier” that can sustain operations if first-island-chain bases are compromised. The island’s indigenous Chamorro population and unique political status as an unincorporated territory also raise governance and sovereignty complexities that influence basing agreements.

Diego Garcia

Diego Garcia, part of the British Indian Ocean Territory, hosts a major joint U.S.-UK military base in the middle of the Indian Ocean. Its location approximately 1,000 miles south of India gives it unrivaled access to the sea lines of communication between the Pacific, Atlantic, and the Persian Gulf. During the Gulf War and the Afghanistan campaign, the base provided critical staging for strategic bombers and naval logistics. However, Diego Garcia’s strategic utility is shadowed by a long controversy: the forced removal of the native Chagossian population in the 1960s-70s. Ongoing legal challenges and international pressure for restitution highlight the human cost that often accompanies island militarization. For more on the legal and ethical dimensions, see Chatham House’s analysis of the Diego Garcia Marine Protected Area.

Taiwan

No discussion of islands in maritime strategy is complete without Taiwan. Though administratively a self-governing island of 23 million people, Taiwan occupies the central position of the First Island Chain, just 100 miles off the Chinese mainland. Control of Taiwan would give China direct access to the Pacific, bypassing the geographical choke points of the Ryukyu Islands and the Philippines. For the United States and its allies, Taiwan represents a vital link in defending freedom of navigation and preventing Chinese maritime dominance. The island is also a major semiconductor manufacturing hub, giving it immense economic leverage. The current cross-strait tensions, with frequent Chinese military drills and U.S. naval transits, underscore how a single island’s fate can shape global strategic stability.

Contemporary Geopolitical Implications

Islands today are at the forefront of great-power competition. Nations are investing heavily in island-based missile systems, radar arrays, and naval facilities. China’s militarized outposts in the South China Sea, Russia’s expansion of Arctic Island stations like Alexandra Land, and India’s development of naval facilities on the Andaman and Nicobar Islands all reflect a race to control physical territory in key maritime zones. These installations allow countries to extend air defense bubbles, monitor shipping, and project power far from their mainland coastlines.

Resource exploration is another driver. The melting of Arctic ice is opening new shipping routes and resource frontiers, making islands like Greenland—which possesses rare earth minerals and potential oil reserves—geopolitically important. In 2019, U.S. President Trump suggested buying Greenland, highlighting its strategic location for early warning systems and submarine monitoring. Similarly, the dispute over the Senkaku/Diaoyu Islands is driven not only by national pride but by potential seabed oil and gas deposits and rich fishing grounds.

Diplomatic tensions over islands can escalate rapidly. The 2016 South China Sea arbitration ruling, while not enforced, complicated China’s claims and intensified naval patrols by the United States and its allies. The island of Yeonpyeong—site of the 2010 North Korean shelling of South Korea—shows how a small island can become a flashpoint for inter-state hostility. These tensions give rise to alliance dynamics, as nations seek to defend their island claims through joint exercises and shared basing agreements.

Environmental Considerations

The strategic value of islands is increasingly affected by environmental factors. Climate change poses existential threats to low-lying island nations such as the Maldives, Tuvalu, and Kiribati, where rising sea levels risk submerging entire territories and their EEZs. This creates legal and strategic uncertainties: if an island is no longer above water at high tide, does it cease to generate a territorial sea or EEZ? Such questions could reshape maritime claims across the Indo-Pacific.

Military and commercial activities also endanger fragile island ecosystems. Coral reef damage from dredging, oil spills, and construction of artificial islands (as seen in the South China Sea) harms biodiversity and jeopardizes the fisheries that local populations depend on. The Spratly Islands, for example, host some of the world’s most diverse marine life but are being degraded by land reclamation. Sustainable development strategies are urgently needed. Some island territories, like the Galápagos Islands in Ecuador, have managed to balance conservation with strategic uses, but many military-occupied islands lack any environmental oversight.

Adaptation is becoming a strategic necessity. Nations are reinforcing island infrastructure to withstand more intense storms and sea-level rise. For example, the U.S. is elevating buildings and installing seawalls on its Pacific bases like Wake Island and Kwajalein Atoll. At the same time, climate-induced migration from sinking islands could create a new class of stateless persons and complicate international maritime boundaries. The intersection of environmental policy and national security is now a core concern for defense planners.

The Future of Islands in Maritime Strategy

Looking ahead, technological changes will both increase and diminish the strategic importance of islands. The proliferation of long-range precision missiles, drones, and hypersonic weapons makes fixed island bases more vulnerable than in the past. However, islands remain irreplaceable as platforms for airfields, radar, and logistical hubs—none of which can be fully replaced by sea-based assets due to cost and persistence. The United States is exploring “distributed lethality” concepts that scatter naval forces across many island locations rather than concentrating them in a few large bases, making the network of island outposts even more important.

International cooperation will be essential to manage island disputes and prevent armed conflict. Multilateral frameworks like the ASEAN Regional Forum and the East Asia Summit offer venues for dialogue, but progress has been slow. Confidence-building measures—such as hotlines between coast guards, joint fishing regulation, and shared environmental monitoring—can reduce the risk of escalation. The recent trilateral security pact between Australia, the United Kingdom, and the United States (AUKUS) includes cooperation on undersea capabilities that depend on island infrastructure in Australia and the Pacific.

Adaptation to climate change will force nations to make difficult choices about which islands to defend or abandon. Some small island states may choose to create artificial elevated platforms or seek to preserve their statehood through legal fictions if their land disappears. The Arctic, meanwhile, will see new island emergence as glacial rebound exposes land that was previously covered by ice, potentially triggering new territorial claims. The strategic chessboard of the world’s islands is far from static—it is being reshaped by natural forces and human ambition alike.

Ultimately, islands will continue to serve as litmus tests for the rules-based international order. Whether through the peaceful resolution of disputes like the one over the Island of Palmas arbitration (1928) or through confrontation, the way nations handle island sovereignty will define the stability of the global commons. For policymakers, strategists, and citizens alike, understanding the role of islands in maritime strategy is not an academic exercise—it is central to navigating the future of geopolitics, trade, and security.