Role of submarines

With significant changes in mission requirements spawned by advances in technology and the threat, the role of submarine remains an important multi-mission component capable of conducting covert operations in forward regions. Submarines are a critical element of  maritime strategy for modern naval warfare planners.

Submarines are significant operational assets. They can contribute significantly in all three areas of maritime operational warfare; sea control, sea denial and maritime power projection. They are a vital element in any serious naval power’s order of battle and, noting the fact that surface forces opposing a submarine threat need to build up a defensive frame that is complicated, expensive and vulnerable, they are increasingly being acquired by medium and small navies.

In addition to their role in anti-submarine warfare, submarines also make good mine layers; and they are suitable for all sorts of odd jobs such as rescue and scouting missions.

Today nuclear energy has made the submarine infinitely more dangerous. The concentration of destructive power in a small warhead has entirely altered the hitherto small “carrying” capacity of the submarine. One submarine today can carry enough explosive power to devastate the entire coastline of a continent. A fleet of submarines, even crudely deployed, can ravage a great power in one salvo.

Thus at the same time that nuclear energy has made surface ships more vulnerable, it has made submarines more mobile, more flexible and more destructive. Their longer range now gives them an increased, and increasingly important, ability to enter waters denied to surface ships by superior air, submarine or even surface power.

A submarine is capable of moving and fighting underwater. They are designed around a pressure hull-a steel tube which is strong enough to withstand water depths of 1,000 meters or more. Submarines have water tanks that are filled and emptied to lower and raise the sub in water. Submarines differ in various ways from their size, to their propulsion as well as weapons.

Developing a submarine is considered one of the most complex military tasks. This is because a submarine is a sealed metal container that contains people and a limited supply of air. They are limited in how big they can be constructed as a result they are crammed with equipment, weapons and supplies. The challenge for any nation developing their own submarines is the fact that the engine, crew and weapons all have to be cramped into a confined space. If the submarine is nuclear powered, a reactor has to be squeezed into the same space.

The submarine’s ability to penetrate a hostile area independently, covertly and for long durations, provided a unique tactical advantage during World War II. Submarines operating undetected near the enemy’s coastline provided a complete picture of the undersea, surface, and near shore military conditions, including enemy force dispositions and preparations. The submarine, with its extremely capable communications ability, operating well inside the enemy’s defensive barriers, provided valuable tactical information to assist Army and Marine Corps field commanders in making timely, informed decisions.


In World War II, the submarine’s ability to circumvent traditional defenses was exploited to the fullest to deliver supplies to American-led guerrilla forces, to rescue pilots (both Allied and enemy) who had been shot down over the ocean, to land and extract coast watchers on remote Pacific islands, to evacuate escaped prisoners of war, to lay mines, and to conduct reconnaissance of potential invasion sites for future Allied actions.

During the Second World War, submarines comprised less than 2 percent of the US Navy, but sank over 30 percent of Japan’s navy, including eight aircraft carriers. More important, American submarines contributed to the virtual strangling of the Japanese economy by sinking almost five million tons of shipping-over 60 percent of the Japanese merchant marine. The first mission executed by Pacific Fleet submarines involved carrying supplies to the defenders of Corregidor. Transportation of intelligence agents to and from enemy-held territory soon followed, but what proved to be the most valuable of those early special operations was the submarine’s ability to relay information of enemy ship movements by coast watchers. As part of their everyday duties, and when not under orders to maintain radio silence, submarines reported the weather, tides, available navigation aids, and enemy force structure in their operating area.

Between 1945 and 1955, the submarine was transformed from a fast surface ship that could hide briefly underwater into a true underwater boat, able to move and fight for weeks on end without ever surfacing. The process began with German U-boats captured by the Allies at the end of World War II. Displaying a number of advanced features that greatly enhanced underwater speed and endurance, such as highly streamlined hulls and snorkels, these boats inspired new thinking in every major navy.

The changes in the US Submarine Force since the end of the Cold War involve shifts in submarine warfighting concepts and doctrine, from the deterrence of global war to the support of US national interests in regional crises and conflicts; from a primary Anti-Submarine Warfare (ASW) orientation against nuclear powered submarines to taking full advantage of the modern submarine’s multi-mission capabilities; from weapon loadouts of primarily MK 48 torpedoes to Tomahawk Land-Attack missiles or other weapons.

Operational survivability is the ability to operate in hostile environments with little or no risk. To avoid most threats, submarines just need to submerge. While surface ships have to be concerned with defence against attack from sub-surface, surface and air launched weapons, submarines rarely do. This relative immunity also allows them to work unassisted. While a surface ship relies on escorts and auxiliaries whenever they put to sea, submarines can operate alone.

Submarines have been employed in various forms of surveillance and intelligence collection throughout the Cold War. The submarine has been a valuable platform for surveillance, intelligence, and warning. This capability comes from the submarine’s ability to enter an area to watch, to listen, collect information without being seen. While satellites and aircraft are used to garner various types of information, their operations are inhibited by weather, cloud cover, and the locations of collection targets. In the future, submarines may also use Autonomous Underwater Vehicles (AUV) or drones to collect intelligence or conduct sustained surveillance of critical regions of the world. These vehicles will be sent out from a submarine to carry sensors into areas where it may not be safe or prudent for the submarine to venture. After fulfilling its mission, the AUV could return to the launching submarine, or transmit the data underwater or to a satellite.

Submarines have long been used for special operations-carrying commandos, reconnaissance teams, and agents on high-risk missions. Most special operations by US submarines are carried out by SEALs, the Sea-Air-Land teams trained for missions behind enemy lines. These special forces can be inserted by fixed-wing aircraft, helicopter, parachute, or surface craft, but in most scenarios only submarines guarantee covert delivery. Once in the objective area, SEALs can carry out combat search-and-rescue operations, reconnaissance, sabotage, diversionary attacks, monitoring of enemy movements or communications, and a host of other clandestine and often high-risk missions. US nuclear powered submarines have repeatedly demonstrated the ability to carry out special operations involving many swimmers.

The operational characteristics of submarines are operational stealth, endurance, freedom of movement, flexibility and lethality. When packaged together they provide mission advantage and potency at sea.


Stopping enemy surface ships and submarines from using the seas is an important mission for submarines. Attack submarines can perform sea denial missions in a variety of scenarios, from general war against a major maritime power, to blockages of enemy ports. Attacks against enemy surface ships or submarines can be part of a war of attrition, where the object is to destroy as much of the opposing naval fleet or merchant shipping as possible, or such attacks can be directed against specific targets.

The significance of a submarine’s operational stealth is arguably growing as countries develop regional/global ocean surveillance systems. Systems which build a wide area maritime picture utilising space, airborne, surface, sub-surface and land based sensing systems-coupled with a network centric warfare requirement for above water assets to have near continuous communication-have amplified the value of the submarine’s operational stealth capabilities.

Covertness bestows the ability to conduct an operation without being detected. The ability to operate covertly is fundamental to the military effectiveness of the submarine. In times of rising political tension, it is a submarine’s covertness that provides a government with a hidden local lethal asset without the penalty of exacerbating or escalating the political scenario.

In 1977, the Argentinean government was pressing the British Government in the hope of gaining control of the Falkland Islands. The British did not want to complicate negotiations by visibly deploying forces, yet they wanted to be prepared in the event that Argentina went ahead and seized the islands. A surface fleet deployment of two frigates and one submarine, DREADNOUGHT, was made and rules of engagement were drawn up, although it was only the submarine that was allowed into the immediate vicinity of the islands: the surface ships remained more than 1000 miles away. Because of the submarine’s covertness, the Royal Navy was able to be deployed to the region without publicity. The Argentineans were never aware of the deployment and after tensions eased, it was quietly withdrawn.

Submarines are also characterised by their operational endurance, i.e. the number of days they can remain at sea unsupported. They have an ability to deploy and remain within an area of operation for a lengthy period of time without the need for re-supply.

Freedom of movement is afforded to the submarine by its stealth and endurance. Freedom of movement is the ability to move from place to place with relative impunity and the ability to access into any chosen area within an area of operations, including areas that are not easily accessed or occupied by other friendly assets, to achieve positional advantage.

Submarines generally have unfettered movement within an area of operations which means they can shift position within the area as the operational or tactical situation changes. Whilst dived they are generally unhampered by rough seas and poor weather.

Stealth, endurance and freedom of movement in combination allow a submarine to exert influence over a very wide area even if it can only deliver its weapons over a small expanse of ocean. Since naval forces do not know the location of a patrolling enemy submarine, they must assume that the submarine could be anywhere and plan their operations accordingly.

A submarine’s wide range of sensor and communication payloads, its effectors and its ability to operate covertly and independently across the area of operations provides a Force Commander with an ability to task a submarine with a number of different mission types as the strategic, operational or tactical situation changes.

Submarines communicate via multiple, complementary RF systems, covering nearly all the military communications frequencies. No one communications system or frequency band can support all submarine communications requirements. Submarine shipboard communications systems consist of RF antennas and radio room equipment, both RF transmitters/receivers and baseband suites. Submarines require a suite of antennas to provide the necessary communications, navigation, and Identification, Friend or Foe (IFF) capabilities. Submarine antennas, as compared to surface ship antennas, are unique in design, shape, materials, and performance due to a submarine’s space and weight limitations, extreme environmental conditions, and stealth considerations. UHF SATCOM provides a relatively high data rate but requires the submarine to expose a detectable mast-mounted antenna, degrading its primary attribute-stealth. Conversely, extremely low frequency (ELF) and VLF broadcast communications provide submarines a high degree of stealth and flexibility in speed and depth.

Effectors such as torpedoes, anti-ship missiles and land-attack cruise missiles, give submarines the ability to bring considerable force to bear on the enemy at the tactical level.

The operational characteristics of submarines are operational stealth, endurance, freedom of movement, flexibility and lethality. When packaged together they provide mission advantage and potency at sea, even against an enemy that is, at least in theory, superior.

Submarines offers both close and distant defence against direct assault, the ability to disperse and deter countering forces, power projection and intelligence gathering without significant risk of provocation and the ability to conduct a wide range of tactically effective operations once hostilities commence. They can be used to effect sea control and sea denial and to contribute to maritime power projection operations.

Changing scenario

The world’s oceans are set to get busier, especially in the Asia-Pacific. For a host of security and economic reasons, American foreign and defense policy will increasingly focus on the Asia-Pacific region in the decades ahead. With over 60% of all U.S. exports going to Asia-Pacific Economic Cooperation (APEC) countries and 40% of total global trade emanating from Asia-Pacific, the United States cannot be an impartial observer of events in the region.

That interest should be heightened by the accelerating military and particularly naval buildup that is playing out across East Asia and the Western Pacific in response to China’s rapid and opaque military modernization efforts. Countries from Vietnam to the Philippines to Japan are responding to Beijing’s recent assertiveness and growing military capabilities by investing in advanced systems of their own. As a result of China’s accelerating military modernisation, regional powers are responding by revamping their force-modernisation priorities, alliances and overall strategic choices.

China’s PLA Navy is transforming towards a regional defensive and offensive type navy with extended A2/AD capabilities and defensive and offensive air power. China calls its comprehensive A2/AD strategy a “counter-intervention”, which is interpreted as denying the United States and its allies the freedom of action in China’s “near seas” by restricting their deployments into theatre (anti access) and denying them freedom of movement there (area denial).

An important aspect of China’s multilayered strategy is the gradual introduction of new classes of submarines-both nuclear and conventional. China is currently operating as many as 45 submarines structured in six different classes: Two classes of indigenously- designed diesel submarines, including the Song class (Type 039) and the Yuan class (Type 041), and four nuclear classes that include the Shang class (Type 093), Jin class (Type 094) nuclear-powered ballistic missile submarines (SSBN) and the follow-on Type 095 nuclear-powered attack submarine (SSN) and Tang class (Type 096) SSBN.

Chinese researchers announced late August 2014 that they have made progress in developing submarines that can travel at supersonic speeds.

Japan and South Korea are prioritising the procurement of new types of submarines. In September 2013, South Korea launched a fourth 1,800-tonne Son Won-il-class (German Type 214) submarine, featuring AIP and combat management systems. South Korea now operates 13 submarines: Nine Type 209 Chang and four Son Won-il-class submarines.

Meanwhile, in October 2013, the Japan Marine Self Defense Force (MSDF) launched its newest submarine, the Kokuryu-the sixth of a planned 10 Soryu-class boats first commissioned in 2009. With its range, endurance, sensors, weapons load and other systems, including the Stirling AIP propulsion system and Harpoon anti-ship missiles, the Soryu class is regarded as the most advanced in Japan’s conventional submarine fleet of 16 submarines.

Most recently, Vietnam received two of six Kilo-class (Project 636) diesel-electric submarines from Russia in 2013-2014, designed for diverse reconnaissance and patrol, anti-submarine and anti-ship missions.

In November 2013, Singapore announced a contract with German shipbuilder ThyssenKrupp to acquire two advanced Type-218SG submarines that will augment existing Archer-class boats and replace ageing ex-Swedish Challenger-class by 2020.

Indonesia, Malaysia and Singapore are also planning to expand or upgrade their submarine fleets. From 2007 to 2009, Malaysia took formal delivery of two French-built Scorpene-class submarines, equipped with underwater-launched Exocet anti-ship missiles. Both submarines are based at the Kota Kinabalu Naval Base in Sabah, East Malaysia, indicating their primary mission to protect Malaysia’s sovereignty in parts of the South China Sea. Meanwhile, Indonesia has ambitious plans to expand its submarine fleet to at least six, and ideally to 12 by 2024.

Recently India’s top-level Defence Acquisition Council cleared INR 900 billion in acquisitions, including INR 530 billion for Project 75I to build 6 AIP submarines in India. The government intends to identify capable shipyards for the foreign partnership within the next 2 months, from among 7 major shipyards (4 of which are state-owned).

India’s submarine fleet currently consists of 16 boats: 10 Russian SSK Kilo (Sindhugosh) Class, 4 locally built SSK U209 (Shishumar) Class, a leased nuclear-powered Improved Akula Class SSN from Russia (INS Chakra), and its own INS Arihant SSBN. Most of the Kilos have been modernized, but readiness rates for India’s existing submarine fleet sits below 40%, and the U209s will have trouble lasting much beyond 2015. India is strong in aircraft carriers but with Pakistan acquiring modern submarines, and Chinese submarine building exploding, expanding, depleting Indian submarine fleet and event of fire incidents is a serious concern. Further India needs to take care of the presence of the Chinese submarines in Indian Ocean.

The world’s oceans are set to get busier, especially in the Asia-Pacific as China expands its sea assets in order to protect its economic supply lines. Since submarines first emerged much work has undertaken to silent submarines and this has resulted in advances in radiated noise management which has made detection by sonar more difficult.

Over the past decade, the operational utility of submarines in East Asia has widened: From anti-submarine warfare to force protection such as close submarine escort missions, intelligence surveillance and reconnaissance to support of Special Forces, and other complementary deterrence and defensive tasks supporting territorial defence.

At the same time, the introduction of submarine-launched anti-ship and land-attack cruise missiles, anti-submarine sensors and weapons, as well as air-independent propulsion systems, have increased their stealth capacity to remain undetected, shortened their target-identification-and-attack cycle and, ultimately, improved their flexibility, mobility, endurance, reach and lethality.

If it comes to a naval conflict in Pacific involving China it will take place close to the land under dispute, or at least close enough for Chinese land-based aircraft and long range missiles to provide support. Unlike America, China does not need aircraft carriers to project power in its waters. America on the other hand needs carrier capability in order to project power in the Western Pacific and Indian Ocean-at least for the time being.

China, like many of the countries in the region, is investing heavily in the development of the submarine as a method of power projection. China is opting for a combination of both nuclear and AIP/Diesel Electric Boats for some time to come. The larger nuclear boats will give the Chinese Navy the range for power projection and a secure launch vehicle for strategic missiles. The silent conventional submarines will be useful both in coastal and shallow waters and provide a realistic deterrent to enemy carriers.

For over a century submarines have had a significant impact on both the preservation of peace and on the conduct of war at sea. But, their deterrent effect will continue to play a significant role in contributing to the security of maritime region-through their preparedness to fight and win at sea.