Why the Strait of Malacca is not another Hormuz

The US-Israel-Iran war has put the Strait of Hormuz in international headlines and sent minds racing. The question of whether other critical straits — such as the Strait of Malacca or the Taiwan Strait — could befall a similar fate is being asked across Asia. Many of the ideas generated from those conversations fail to account for critical variations in the strategic landscape and military geography among the various chokepoints under consideration. We have every reason to be concerned, but it is important to understand the real risks.

It is not particularly helpful to think about the current conflict in terms of the Strait of Hormuz. Instead, we need to think about questions of sea control along the sea lanes that begin in the Persian Gulf, pass through the Strait of Hormuz, enter the Gulf of Oman and then radiate across the Indian Ocean. According to U.S. Naval War College professor Milan Vego, sea control is “the ability to use a given part of a body of water and its associated air space for military and nonmilitary purposes in time of open hostilities”.

Before launching the first strikes on Iran on 28 Feb, the US Navy had already removed its naval forces from the Persian Gulf. Therefore, Iran was easily able to use its mosaic of highly survivable anti-ship weapons — missiles, surface and air drones, fast-attack craft, uncrewed submarines, sea mines, etc. — to assert sea control over the Persian Gulf, the Strait of Hormuz and the northern reaches of the Gulf of Oman. While the US proceeded to eliminate Iran’s conventional navy, these “anti-access” weapons retain much of their original capability under the control of the Islamic Revolutionary Guard Corps (IRGC).

By striking commercial vessels underway and in port across this vast region, Iran established basic rules for commercial shipping. As the regional chokepoint where Iran could focus its most firepower, the Strait of Hormuz became the control valve for shipping. Those who followed Iranian rules could traverse; those who did not did so at high risk.

Beyond Iran’s littoral, the US retained command of the sea. This was shown early in the conflict when the US Navy sank the Iranian frigate Dena near Sri Lanka and forced two other Iranian Navy ships to seek shelter in neutral ports. When the US established its own blockade of Iranian ports, it could enforce it at locations of its choosing. The first ship it seized was in the Gulf of Oman, but the next two were far away, on the other side of India.

The Strait of Malacca and the Strait of Hormuz are both international straits that overlap by the territorial seas of several states and carry critical levels of global trade.  That is perhaps where the similarity ends. 

The Strait of Hormuz is the only maritime route between the Indian Ocean and the Persian Gulf. Therefore, closing it isolated an entire region from the economic benefits of sea connectivity. In contrast, the Strait of Malacca is not the only passage from the Indian Ocean to the seas to which it connects: the South China Sea and the Java Sea. Routing around the Sunda Strait only costs ships a few days of transit time. The Lombok Straits are further away but also feasible. The major port of East Asia could even be reached by routing entirely around the Indonesian archipelago. 

A more important difference is the straits’ military geography. Iran has been, for years, locked and loaded to close the Strait of Hormuz. This has been a critical component of its strategy to deter the type of attacks launched by the US and Israel. None of the Strait of Malacca states have elected this path. 

While the Singapore Armed Forces are top-notch, and both Malaysia and Indonesia have been investing in the “anti-access” military systems needed to gain local sea control, the forces of those states have not been designed or postured to close the Strait of Malacca. More importantly, none of those states would find such a strategy useful. Lacking enemies that they might need to punish or deter by shutting off trade, they would only be hurting themselves. They are strategically aligned to keep the Strait of Malacca open.

While Indonesian officials have recently made comments about charging tolls for use of the Strait of Malacca, they also walked those back by clarifying that they were just jokes or speculation. While Indonesians have a longstanding socio-legal perspective that the sea lanes passing through their archipelago are both sovereign waters at the core of the national territory and that foreign access to those straits is a source of insecurity, they also understand the net benefits that international maritime law delivers to their nation, and that interrupting trade would be contrary to the legal bargain their leaders wisely struck during the negotiation of UNCLOS. Thus, such a toll system is highly unlikely. If it were enacted, it would be problematic, but also very different from the wartime blockades around Iran.

Although open naval warfare remains (thankfully) unlikely in Asia, the most likely sources of maritime conflict are the geopolitical hotspots on China’s ocean-facing periphery — the East China Sea, the Taiwan Strait and the South China Sea. If those tensions were to boil over into open conflict, it would not be another asymmetric fight between a global maritime power and a coastal anti-access force as we see in the Middle East.

The US and China both operate large blue water navies. Those are backed up by shore-based anti-access weapons in China and in the US and allied territories along the Pacific Ocean’s first and second island chains. Thus, the first contest of these navies will be to gain sea control over the bodies of water most pertinent to the conflict. Fighting would certainly be intense in the East and South China Seas and will likely be similarly fierce in the Philippine Sea. Some fighting should be expected in the Indian Ocean as well.  At least in the open weeks of conflict, the navies will have few resources to do much else.

In the hypothetical scenario where the US and China engage in open warfare, it should be assumed that they would not leave each other’s commercial ships unmolested.  

The Strait of Malacca and other regional chokepoints force vessels to concentrate in relatively constrained spaces and therefore appear more vulnerable, yet trying to block all the vessels that normally use them would require more ships that either the US or China could peel off from the navy-vs-navy fight. Furthermore, these straits are within the territorial waters of the coastal states. In its recent conflicts with Iran and Venezuela, the US has respected those rights, only interdicting vessels in international waters. 

Both the US and China could be concerned that their opponent might enlist the help of a Southeast Asian state to lend its littoral position to an effort to close a strait from the shore. However, that would clearly cancel that state’s neutrality status, a position none would want to take. Plus, it is questionable how useful this would be.  Very little Strait of Malacca traffic directly serves the US, and China has already developed the alternate routes and taken resiliency measures to minimise its so-called “Malacca Dilemma”.

This is not to argue that there is nothing to be concerned about. Great power competition is likely to intensify. This competition will take place across the globe’s geopolitical stage, especially on the world’s oceans. While straits are key features that will present certain vulnerabilities, the contest will be broader. Rather than focusing on the possibility of military closures of straits, we should prioritise readiness to cope with other tools of maritime statecraft we already see in play, such as tariffs, sanctions and offshore blockades. These will likely be amped up and arguably more difficult to deal with.

Related: What if the Taiwan Strait were blockaded? | From Malacca to Taiwan: China’s chokepoint problem