However, the configuration of Southeast Asian seas as enclosed and semi-enclosed seas (‘narrow seas’) could affect and influence maritime defence in the area.
Enclosed and semi-enclosed seas are defined in the United Nations Convention on the Law of the Sea (UNCLOS) as ‘a gulf, basin or sea surrounded by two or more states and connected to another sea or the ocean by a narrow outlet or consisting entirely or primarily of the territorial sea and exclusive economic zones of two or more coastal states’. As argued by Milan Vego of the US Naval War College, an enclosed sea ‘lies wholly within the continental shelf, and is surrounded by a landmass except for a strait or several straits that connect it to an ocean or another enclosed or semi-enclosed sea’. A semi-enclosed sea is more characterised by large tidal ranges that are oceanic in nature.
Vego defines narrow seas militarily as ‘bodies of water that can be controlled from both its sides’. As such, maritime forces operating in narrow seas are more open to attack from the land-based weapons of coastal states than in open seas. This makes defence of, and in, narrow seas different from that of the open seas, including those in Southeast Asia.
A successful defence of narrow seas relies on two characteristics: a lack of physical space and a closer proximity to land. As Vego asserts, these would bring consequences for maritime forces in terms of their manoeuvrability, combat intensity, battle space spectrums and the use of airpower. In narrow seas, large surface combatants are much more difficult to manoeuver due to depth, width and access restrictions.
Maritime combat operations will also be more saturated and intense since most narrow seas are relatively within the effective range of land-based weapons. Operations in narrow seas can also be multi-dimensional across all spectrums of battle space — air and space, surface and subsurface, coastal, and electromagnetic — as the propensity to confront the whole fleet of a coastal state is much greater than in open seas.
Furthermore, narrow seas are still within the range of land-based combat aircraft, which makes it relatively easier for coastal states to challenge sea control and conduct sea denial operations without needing to have robust naval combat assets at sea. Sea control aims to use the sea for oneself, and if necessary, prevent the enemy from using it, whereas sea denial aims to deny the enemy’s fleet from operating in a particular sea area, but does not aim to use the sea for oneself.
Narrow seas often constitute the whole of the territorial seas and exclusive economic zone of a coastal state. This makes control over narrow seas desirable due to social and economic necessities. Further, in narrow seas a weaker coastal state can effectively challenge a superior maritime power using an array of ‘asymmetric’ maritime capabilities such as naval mines, coastal missile batteries and submarines.
In Southeast Asia, there is no shortage of narrow seas to influence regional maritime defence. Historical precedents from World War II offer salutary examples of defence in narrow seas. The capital ships of the British Royal Navy, the HMS Prince of Wales and HMS Repulse, were sunk entirely from the air for the first time in combat in the South China Sea by Japanese bombers off the east coast of Malaya. Hence, control over narrow seas often requires control over the air above and water column below.
Amid the growing maritime competition between the key powers in the South China Sea, the coastal states seem to be gearing themselves up to meet this challenge. Submarines are already in the fleets of Indonesia, Singapore and Malaysia, and at the top of Vietnam’s shopping list. Thailand and the Philippines are also mulling over submarine acquisition. Maritime strike aircrafts, like the Sukhoi Su-30, have entered the inventories of Indonesia, Malaysia and Vietnam.
More importantly, coastal states could also exploit the islands in the area by building infrastructures to support exertion of sea control over the surrounding waters. Control over maritime choke-points and passes are also crucial as they guarantee access for maritime powers to transit in regional narrow seas.
Maritime powers, too, need to adapt to more agile and versatile platforms, like corvettes, frigates and littoral combat ships. Without the latter acting as an adequate escort, deploying large platforms like amphibious assault ships or aircraft carriers in hostile narrow seas is very risky.
Presumably, more investment toward these capabilities might be more destabilising as they could only be used for war-fighting purposes. This could generate misunderstanding and miscalculation, especially when they are deployed in disputed narrow seas, like the South China Sea.
However, this development should not be a cause for alarm. Regional maritime forces still have a long way to go to transform platforms into real capabilities. There are some important questions about their capacities to effectively operate them, ensure safety during their operational use, as well as quality maintenance. Unless these questions are properly addressed, one should doubt the utility of these capabilities beyond being a psychological deterrent.
Ristian Atriandi Supriyanto is a Senior Analyst with the Maritime Security Programme at the S. Rajaratnam School of International Studies, Nanyang Technological University. He was previously a researcher at the Centre for East Asian Cooperation Studies, University of Indonesia.
This article was first published here as RSIS Commentary No. 184/2012.