A Vulnerable Lifeline
In 1897, Alfred Thayer Mahan asserted, “Whoever controls the sea controls the world”. In 2024, the maritime industry is growing at around 1.5 times the global economy’s growth rate. It is the bloodstream of the global economy, carrying over 90% of the world’s goods across oceans [1]. Critical shipping lanes like the Strait of Malacca, the Suez Canal, and the Panama Canal serve as lifelines for nations, enabling the movement of goods, energy, and raw materials. Countries like China, India, and the United States owe significant portions of their GDP to seaborne trade.
With such immense power concentrated in maritime trade, the vulnerability it creates for nations has not gone unnoticed. Nations have long recognised this strategic advantage of strangling these economic lifelines to destabilise rival nations. This is the essence of maritime trade warfare which is nothing but a calculated assault on the arteries of global commerce. From privateers raiding merchant ships to blockades crippling economies, and now to the weaponisation of trade policies and sanctions, the methods have evolved. Still, the goal remains the same: destabilisation through economic coercion.
The Early Weapons
Before the World Wars, privateers, essentially state-sanctioned pirates were a preferred economic warfare tool. These privately owned ships disrupted enemy trade by capturing merchant vessels, also called the ‘guerre de course’ strategy—this approach, prominent during the 18th and 19th centuries, aimed to weaken adversaries through economic attrition. However, the 1856 Declaration of Paris sought to end the guerre de course by outlawing privateering. Notably, the United States declined to sign, because its Navy was small, guerre de course offered one of the few options by which it could attack a more powerful naval power. [2]
Maritime Warfare During the World Wars
The World Wars brought a strategic and technological evolution in maritime trade warfare. In World War I, Britain’s naval blockade of Germany was a cornerstone of its strategy, effectively cutting off supplies and crippling the German economy. This was countered by Germany’s use of unrestricted submarine warfare, targeting British and Allied supply lines with devastating effect.
In World War II, maritime trade warfare escalated further, the USA-Japan conflict being the most notable case. The infamous attack on Pearl Harbor was not only a military strike but also a calculated response to the U.S. oil embargo, which had severely hampered Japan’s resource access. Beyond Pearl Harbor, Japan employed aggressive naval tactics to secure vital trade routes and other resource-rich Southeast Asian territories.[3]
Meanwhile, the Allies refined their maritime strategies, leveraging convoys and advanced anti-submarine technologies to safeguard supply lines. Germany's use of U-boats in the Atlantic resulted in extensive losses for Allied merchant fleets, but the introduction of sonar, depth charges, and air patrols eventually turned the tide. The Battle of the Atlantic became a defining point of maritime trade warfare, with control of the seas dictating the flow of resources and ultimately influencing the war's outcome.[2]
This period saw the direct use of naval forces to disrupt trade and the broader weaponisation of maritime policies, such as embargoes and resource blockades. Control over trade routes and resource access became as critical as victories on the battlefield, reshaping the role of maritime strategy in global conflicts.
The Modern Waters: USA-China
The U.S.-China trade war that began in 2018 is one of the most consequential economic conflicts of the 21st century. It has profoundly impacted both the nations’ economies, largely through disruptions in maritime trade. The impact was not confined to the USA and China, it also disrupted global maritime shipping through tariffs, export restrictions, and supply chain interruptions.
The U.S. economy, heavily reliant on imports from China, saw significant disruptions. By mid-2018, the imposition of tariffs on Chinese goods led to higher import prices. This inflationary pressure was partly absorbed by businesses and partly passed on to consumers, leading to higher retail prices domestically. Major U.S. ports, such as the Port of Los Angeles and the Port of Long Beach which are key gateways for Chinese imports, reported significant volume declines. Industries that rely on components imported from China, such as automobile and tech manufacturing, suffered supply shortages. Factories faced delays due to disrupted shipping schedules, which slowed production cycles and raised costs. [4]
China, the world’s largest exporter, was vulnerable to the direct effects of reduced maritime trade with the U.S. Maritime trade accounts for over 60% of Chinese export logistics, and this contraction significantly impacted Chinese ports like Shanghai and Shenzhen, which saw lower container throughput. With reduced demand for exports to the U.S., Chinese shipping companies, including COSCO Shipping, experienced surplus capacity. This led to lower freight rates and financial losses for shipping operators. The drop in maritime trade contributed to China’s GDP growth slowing to 6.1% in 2019, the lowest in nearly three decades [5]. Reduced demand from the U.S. rippled through China’s manufacturing sector, leading to layoffs and factory closures, particularly in coastal regions heavily reliant on trade.
The U.S.-China trade war also caused shockwaves beyond their economies, fundamentally altering global shipping patterns. Companies seeking to avoid U.S.-China tariffs relocated manufacturing to countries like Vietnam, Thailand and India. This created new trade routes, with Southeast Asian ports experiencing increased volumes. Vietnam’s exports to the U.S., for example, rose by 35% in 2019, making it one of the largest beneficiaries of the trade war [6]. The strategic decoupling of U.S.-China supply chains led to inefficiencies, as new shipping routes were longer and less optimized, increasing fuel consumption and transit times. This added strain on global shipping logistics, particularly during the pandemic, worsened the supply chain crisis of 2020-2021.
The European Union Sanctions on Russian Maritime Trade
The European Union's sanctions on Russia, imposed in response to its military actions in Ukraine, had significantly disrupted global maritime trade. A key component of these sanctions was the reduction in seaborne imports of oil from Russia which took effect on 5th December, 2022. In the first half of July 2024, these exports fell to 2.9 million barrels per day, marking the lowest level since December 2022 [7]. The sanctions also compelled Russia to offer its Urals crude oil at discounted prices, significantly reducing Russia's oil export revenues [8].
These sanctions brought a shift in global maritime trade patterns as well. Russia’s need to redirect its oil exports to distant destinations, such as Asia, increased transportation costs and influenced global oil price dynamics. Countries like India increased imports of Russian oil to take advantage of discounted prices, however, the shortages led Indian refiners, such as Bharat Petroleum Corp (BPCL) to seek alternative sources from the Middle East. [9] [10]
Further, in response to the sanctions, Russia developed a “shadow fleet” of vessels to clandestinely transport oil, circumventing international restrictions. This fleet, estimated at over 1,400 ships by October 2023, poses substantial risks to maritime security and the environment due to older, inadequately maintained vessels [11].
India’s Play in IOR
India’s maritime positioning is uniquely strategic, commanding access to the Indian Ocean, which serves as a critical artery for global trade and energy supplies. With nearly 80% of the world’s oil shipments and over 60% of seaborne trade passing through the Indian Ocean Region (IOR), India’s role in maintaining stability and security is paramount.
A prime example of India’s strategic maritime influence is the 2023 rice export ban, which disrupted shipping routes across the Indian Ocean. The decision, driven by domestic priorities like stabilizing prices and ensuring food security, highlighted India’s role as the world's largest rice exporter. With importing nations in Africa and Southeast Asia reliant on Indian shipments, the ban caused a 12% spike in global rice prices, showcasing the interconnectedness of maritime trade and food security [12].
However, India faces strategic challenges due to the increasing presence of China in the IOR, often referred to as the “String of Pearls” strategy. This includes the development of Chinese-funded ports and infrastructure projects in countries like Sri Lanka (Hambantota), Pakistan (Gwadar), and Myanmar (Kyaukpyu), which encircle India and potentially threaten its security.
India has responded by enhancing its naval presence and forging partnerships through initiatives like the Quad Alliance (with the U.S., Japan, and Australia) and the Malabar Naval Exercises that serve as a demonstration of India’s readiness to counterbalance Chinese influence and secure critical chokepoints like the Malacca Strait [13]. Furthermore, the Sagarmala Program, aimed at modernising ports and reducing logistics costs, is a strategic move to strengthen coastal trade hubs and integrate them with industrial clusters to enhance influence on global networks.
The Concluding Waves
The evolution of maritime trade warfare, from the era of privateers to the modern battleground of sanctions and economic coercion, underscores the enduring significance of the sea in global geopolitics and commerce. Maritime trade is not just the bloodstream of the global economy but also a potent instrument of power, capable of shaping the fortunes of nations. The patterns remain clear, control of the seas equates to influence over the world.
In the modern era, diplomacy has replaced direct military attacks, but the stakes are higher than ever in a globalised, interconnected world. The U.S.-China trade war demonstrated how economic skirmishes can disrupt global supply chains, while the European Union sanctions on Russian maritime exports reshaped global oil markets and security dynamics. Meanwhile, India’s strategic positioning in the Indian Ocean has cemented its role as a critical player in maritime geopolitics, balancing domestic priorities with regional stability.
Looking to the future, maritime trade warfare is likely to take on new dimensions, driven by technological advancements and the intensifying geopolitics of an evolving multipolar world. Cyberattacks targeting shipping systems, the militarisation of autonomous vessels, and the strategic use of data analytics to predict and manipulate trade flows would become central elements of future conflicts.
In this increasingly complex landscape, nations will need to adapt to secure their economic lifelines and ensure the stability of global trade networks. Multilateral cooperation, investment in resilient infrastructure, and the enforcement of international maritime law will be critical to mitigating the risks of economic destabilisation. However, as history has shown, the seas remain a stage for both collaboration and conflict, and the balance between these two forces will shape the future of maritime warfare and the global economy itself.
Article By:
Kunjal Patwari
Editor
PES MUN Society
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