At the end of April, Indonesia’s finance minister prompted a sharp reaction when he suggested, half-jokingly, that Indonesia, Malaysia and Singapore might impose a toll on vessels transiting the Strait of Malacca. The remark was quickly walked back by foreign ministry officials who reiterated support for freedom of navigation, but it exposed a deeper worry: could the world’s narrow maritime passages be turned into tools of political or economic coercion?
The Strait of Malacca, the tight channel linking the Indian Ocean and the Pacific, is one of the globe’s most important shipping routes. Around 22 percent of international maritime trade moves through it. That concentration of traffic makes such straits attractive levers of influence: controlling or threatening to disrupt them can have outsized consequences for regional and global supply chains.
Recent events have underscored that danger. The Center for Strategic and International Studies warned that non-state actors now have the ability to inflict serious disruption on global trade, pointing to attacks by the Houthi militia in the Red Sea. Many shipping companies rerouted vessels around the Cape of Good Hope to avoid the Suez Canal, a change that lengthened voyages, raised costs and strained supply chains and prices worldwide.
Analysts see these developments as part of a broader shift in geopolitics. Some experts argue we are witnessing a ‘return of geography’ in which physical choke points — straits such as Hormuz, Malacca or Taiwan — are no longer neutral corridors but strategic instruments. The more vital a route is to trade and the fewer practical alternatives that exist, the more leverage control of that route confers.
International law is clear on paper: under the United Nations Convention on the Law of the Sea, maritime straits of international importance are subject to a principle of free transit. Warships and commercial vessels should be allowed to pass unhindered, and coastal states cannot levy tolls on natural straits the way canal authorities can on artificial waterways such as the Suez or Panama canals. A blockade of an international strait would be a serious breach of international law.
The tension arises in practice. International law only works if states choose to respect it. Past incidents in the South China Sea show that even court rulings can be ignored, and some governments may be willing to use geographic advantage to advance political aims. At the same time, modern tactics mean that a huge navy is not required to create disruption. Small boats, missile strikes, drones, and other asymmetric tools can impose significant costs on commercial shipping and force detours that ripple through global markets.
That said, states that attempt to block or restrict access to vital waterways also risk harming themselves. A blockade of the Taiwan Strait or Malacca would not only damage global trade partners but would likely inflict heavy economic blowback on the blocking power as well. There are alternative routes — for example, the Sunda Strait or the Lombok Strait in Southeast Asia — but they are longer and more expensive, and may not fully compensate for the loss of the main channels.
The vulnerability is amplified by the structure of modern supply chains. The ‘just-in-time’ logistics model minimizes inventory and relies on predictable, rapid deliveries. Even short interruptions can cascade into production slowdowns, higher prices, and shortages. That fragility is why the CSIS cautioned that threats to the Strait of Hormuz or Malacca are not isolated problems but symptoms of systemic exposure: the global economy depends on a handful of maritime chokepoints.
The strong, immediate pushback from Singapore, Malaysia and Indonesia to the toll suggestion illustrates both the sensitivity of the issue and how tempting it can be for states to view geographical control as leverage. It also highlights how dangerous any erosion of the accepted rules would be for international trade and economic stability.
In short, while laws protect freedom of navigation, geopolitics and the evolving character of conflict mean that maritime channels can increasingly be weaponized, intentionally or not. Preparing for that reality requires diplomatic commitment to uphold legal norms, cooperative regional security arrangements, resilient supply-chain planning, and recognition that the world economy’s dependence on a few narrow passages is a strategic vulnerability as well as a logistical fact.