Flashpoints | Security | Southeast Asia

China and Maritime Chokepoints: Hormuz, Malacca, and Indo-Pacific Vulnerability

Disruptions in Hormuz immediately generate concern regarding Malacca, another vital maritime chokepoint.

The Strait of Hormuz became a focal point of recurring regional tensions and broader power struggles following United States and Israeli strikes on Iran on February 28 and beyond. Heightened Iranian restrictions on shipping and Tehran’s blockade of the waterway have renewed global concern over strategic maritime chokepoints, shifting analytical and policy attention toward other critical corridors, including the Strait of Malacca. 

While the Strait of Hormuz is indispensable to global energy trade as a conduit for key commodities – most notably oil and liquefied natural gas (LNG) – the Strait of Malacca links the Indian and Pacific Oceans and functions as the principal maritime corridor connecting the Middle East, Africa, and East Asia.

The two straits function as critical arteries of the global maritime economy, but they are not structurally identical chokepoints. Hormuz functions mainly as a supply-concentrated energy chokepoint, through which a large proportion of global oil and LNG exports are physically concentrated. By contrast, Malacca functions as a network-dependent systemic trade chokepoint, embedded within dense manufacturing, logistics, and supply-chain interdependencies across East Asia and beyond. Disruptions in Hormuz therefore tend to produce immediate energy-price effects, whereas disruptions in Malacca are more likely to generate cascading systemic effects across both energy and industrial supply chains.

Disruptions in Hormuz immediately generate concern regarding Malacca, given that energy flows originating in the Persian Gulf continue through Southeast Asia toward major markets such as China, Japan, and South Korea, as well as other emerging and industrializing economies in Asia. Approximately 23 million barrels of oil transit the Strait of Malacca each day, with roughly four-fifths of China’s imported oil moving along this route. This interdependence calls attention to globalization’s reliance on secure maritime shipping lanes, a structural condition that is unlikely to materially change in the foreseeable future.

Following Iran’s blockade of Hormuz and the subsequent so-called “double blockade” by both Iran and the U.S., daily shipping traffic through the strait reportedly fell from approximately 130-140 vessels to 5-10. Overall traffic declined to around 5 percent of pre-conflict levels by the end of April and is estimated to have fallen below 4 percent in subsequent assessments.

Despite overwhelming U.S. military superiority, normal shipping conditions were not restored owing to broader regional constraints and operational limitations. As vessels accumulated on both sides of the strait awaiting safe passage, the crisis increasingly exposed the fragility of the wider maritime trading system.

The Strait of Malacca, situated between Indonesia, Malaysia, and Singapore, functions as one of the world’s busiest shipping corridors and a critical conduit for energy exports from the Persian Gulf to East Asia. Its strategic significance, however, extends well beyond hydrocarbons. Manufactured goods, electronics, food supplies, and raw materials flow through the strait in vast quantities, embedding it deeply within global production and consumption networks. Consequently, a disruption in Malacca could generate economic consequences broader in scope than those associated with Hormuz, reflecting its dual role in linking both energy flows and global manufacturing supply chains.

Alternative Routes and Southeast Asian Vulnerabilities

Narrowing to about 2.7-3 km at its tightest point near the Phillips Channel between Singapore and Indonesia, the Strait of Malacca foregrounds the fragility of global maritime trade. Any disruption or closure of the waterway would carry significant consequences. Unlike overland transportation networks, maritime shipping depends on a limited number of narrow chokepoints that are difficult to substitute. If the Strait of Malacca becomes impassable, the 200 to 300 vessels that transit it daily, amounting to more than 90,000 annually, will have to reroute through alternative passages, notably the Lombok, Sunda, and Makassar Straits in the Indonesian archipelago.

These routes are strategically significant in their own right. The Lombok Strait, located between Bali and Lombok, is sufficiently deep to accommodate large supertankers and naval vessels that may struggle to transit Malacca. The Sunda Strait, positioned between Java and Sumatra, offers an alternative corridor, although its shallow sections and complex geography reduce navigational efficiency. The Makassar Strait, running between Borneo and Sulawesi, connects to the Lombok route and functions as a key secondary maritime corridor.

Although these alternatives could partially absorb redirected traffic, they are substantially longer. Rerouting through these waterways raises concerns about congestion and potential logistical bottlenecks. Such diversions increase fuel consumption, insurance premiums, transit times, and overall operational costs, as demonstrated during the Bab el-Mandeb disruptions in late 2023, while placing additional strain on regional maritime infrastructure and naval security systems.

For Southeast Asian states, the risks are particularly acute. Indonesia occupies a uniquely strategic position, as many alternative maritime corridors pass through waters under its jurisdiction. A disruption in Malacca would redirect traffic through the Lombok and Sunda Straits, potentially enhancing Indonesia’s geopolitical leverage and increasing maritime revenues, while also intensifying political and economic pressures associated with its role as more than a littoral state hosting key waterways. Indonesia’s manufacturing sector is likewise dependent on the uninterrupted flow of strategic components for export-orientated industries. Rerouted shipments increase port congestion, raise freight rates, extend production delays, and exacerbate customs processing backlogs.

Mounting security pressures would likely follow as well. Increased traffic volumes elevate risks of piracy, human trafficking, smuggling, illegal, unreported and unregulated (IUU) fishing, and maritime accidents, while placing additional strain on Indonesia’s navy and coast guard. Against this backdrop of heightened operational and security pressures, debates over the governance of maritime traffic have also become more politically sensitive. 

The Indonesian government recently attracted attention and criticism following remarks suggesting a potential toll or tax on shipping passing through the Strait of Malacca, although the Finance and Foreign Ministries later clarified that Jakarta has no plans to impose such a levy. Singapore’s Foreign Minister Vivian Balakrishnan rejected the proposal, stressing that passage through the straits must remain open and free for all users.

Malaysia would also experience significant economic and strategic repercussions from a Malacca closure. Azmi Hassan of Malaysia’s Akademi Nusantara has argued that the “Straits of Malacca and the South China Sea are much more important and critical compared to the Strait of Hormuz.” 

Malaysia’s ports and export-orientated industries are deeply integrated into regional maritime trade networks. Any disruption to shipping through Malacca would reduce commercial activity, strain logistics sectors, and increase import costs. A Malacca chokepoint crisis is likely to generate higher domestic electricity bills, rising transportation costs, and surging prices for fertilizers and food for the........

© The Diplomat