Undersea Warfare


14th Mar 2011

 Undersea Warfare


In the previous issue of Asia Pacific Defence Reporter we outlined the roles that submarines perform in peacetime. These roles were broken down into four different categories; prevention of war, preparation for war, naval diplomacy and constabulary tasks.
This month we look at the roles a submarine performs in wartime.
Most submarine wartime roles are offensive in nature and are carried out very close to or inside enemy waters. In the lead up to war, submarines can be forward deployed to conduct battle space preparation tasks such as reconnaissance and Rapid Environmental Assessment (REA) and, when war is imminent, conduct measures such as Special Forces insertion & support and offensive mine laying. Once war has commenced, land strike, anti-shipping and anti-submarine tasks can be undertaken.

Battle Space Preparation  Reconnaissance and REA Operations

In the lead-up to war, submarines will be tasked to perform a variety of reconnaissance tasks.
Reconnaissance involves acquiring and reporting on what is often specific one-time and time-sensitive information about the enemy - including information about force dispositions, including disposition in ports, and their intentions along with other events of military interest.
Reconnaissance tasking by submarines was carried out by both participants in the Falklands War. On the 28th March 1982, British intelligence intercepted a signal ordering the submarine ARA SANTE FE to conduct beach reconnaissance off Port Stanley in preparation for disembarkation of Argentinean forces. On the British side, one of HMS CONQUEROR’s first tasks on arriving in the South Atlantic Area of Operations (AO) was to conduct reconnaissance on the Argentine Marine positions at Grytviken and Leith on South Georgia. HMS SPARTAN also conducted reconnaissance of Port Stanley and, no doubt amongst other things, observed the Argentinean vessel ARA CABO SAN ANTONIO laying mines to the east of Port Stanley harbour. It is noted that the Commanding Officer of HMS SPARTAN did ask for permission to attack but this was denied to avoid opening the shooting war too soon and compromising diplomatic efforts then still being pursued. None the less, the covert observation of the Argentine operations provided a valuable warning that the harbour had been mined.
Pre-war Information, Surveillance & Reconnaissance (ISR) missions can also include the detection and subsequent tracking of enemy submarines as they attempt to depart their ports.
A variation on the ISR theme is the collection element of the REA cycle, particularly when covertness is required. Most submarines are fitted with sensors required to collect geospatial information such bathymetry, bottom classification data, sea surface data, water column data, current and tidal stream data, turbidity data, ambient noise information and meteorological data.
Many submarines also have some inherent capacity to detect the presence of mine-like objects. They also have the ability to deploy purpose-configured Autonomous Underwater Vehicles to extend their collection capability to shallow and very shallow water. Information collected and reported can then be processed and then dissemination to provide own forces with a “now cast” understanding of the likely impact of the environment on operational and tactical performance. The output of the REA is a single “Recognised Environmental Picture” that coherently pulls together meteorological, oceanographic, hydrographic and geographic information from numerous sources.
General surveillance and intelligence collection will also be carried out during reconnaissance and REA operations.

Deployment of Special Forces

In the lead up to war, and particularly once war is considered to be imminent, Special Forces can be very useful for land based ISR, REA, counter-mining, mine countermeasures and sabotage operations. Deployment pre-hostilities also allows Special Forces to be in a position to secure staging areas, attack coastal missile defences prior to scheduled air strikes, provide forward air control, conduct diversionary attacks and conduct combat search and rescue missions once a conflict has commenced.
Submarines are an extremely effective platform for the covert deployment of Special Forces, predominantly on account of their stealth and freedom of manoeuvre. They also have the capacity to provide support to these forces once they have been landed.
During the initial stages of the Argentinean landing of troops on the Falkland Islands ARA SANTA FE launched a small group of Special Forces swimmers who were tasked to reconnoitre the Marine’s chosen landing beach at the Island’s capital of Port Stanley. Two and half hours later these men were used to guide Marine Amtracs to their landing points.
One of HMS CONQUEROR’s first roles in the Falklands War was to conduct surveillance (Harper, 1994) around South Georgia and then land a party of Special Boat Service personnel on the northern part of the island. The SBS unit did not end up landing (Rossiter, 2007) but this does not detract from the utility the submarine provided.
In his book, “Stealth at Sea”, Dan Van de Vat’s reported that a British conventional submarine ventured into the Persian Gulf during operation “Desert Shield” on a mission so secret that the US Military were only made aware of it after they detected it. Van der Vat then went on to infer that the submarine was being used to place British Special Forces behind Iraqi enemy lines.
Note that it is not necessary for Special Forces to be onboard a submarine when it sails in order for this sort of tasking to be ordered. It is possible to embark Special Forces on submarines already deployed. Special Forces have been deployed to submarines by parachute from fixed wing aircraft or by rappelling from helicopters.

Offensive Mine Laying

Once war is considered imminent, submarines can be used to lay mines at the entrance to vital ports and harbours, around anchorages or in sea lanes in order to contain enemy forces, cause congestion in enemy ports, force diversion of traffic and even stop cargo flow. They can do so with precision and complete covertness.
Mines can be carried by submarines internally and launched through the torpedo tubes or externally in conformal mine belts. Whilst most mines laid from submarines would be bottom influence mines, they can also “lay” torpedo based mobile mines which can be launched and “swim” into shallow ports and channels not otherwise accessible by a submarine.
However, mine-laying comes with a high opportunity cost noting that, unless mine belts are employed, mines would be loaded at the expense of torpedoes and missiles. This is particularly so where only a limited number of submarines might be available to operational commanders. None the less, it may well be a very useful wartime role for the older, less capable, submarines retained in some country’s military order of battle.
The most recent known example of a submarine laying mines comes from the 1971 Indo-Pakistani war. On the 14th of November the Pakistani submarine PNS GHAZI, loaded with torpedoes and mines, sailed from the port of Karachi to the Bay of Bengal area on Indian’s eastern seaboard. On the 3rd December she was believed to be conducting a mine lay off the Indian naval port of Vishakhapatnam, where the Indian Carrier INS VIKRANT was believed to be present. An Indian destroyer INS RAJPUT was operating in the area at the same time and dropped depth charges in response to a water disturbance. It is unlikely that INS RAJPUT was successful with its attack but about half an hour later a loud explosion was heard. It is believed the submarine, having been disturbed by the destroyer, may have fallen victim to one of her own mines. A British merchant ship, BRITISH CRUSADER, was subsequently damaged by a mine about a mile from the submarine wreck.

Operations after the Commencement of War
Tactical Land Strike

Once war has commenced, submarines can conduct tactical land strikes.
The objective of land strike is to destroy or incapacitate enemy Command & Control facilities, strategic air defences, intelligence systems, infrastructure, key production facilities and military forces. Land strike operations are joint operations with targeting information provided by strategic commanders and missile attacks co-ordinated in time and space across a force forces to produce a synergistic approach.
Submarine plays an important part in the overall land strike approach Submarines can deploy into an AO in situations where other units may not be able to due to a lack of sea or air control. They can then attack targets that incapacitate enemy defences thus making an area safer for other more vulnerable units to enter. They can also operate very close to shore which provides surprise advantage when striking the most sensitive of military targets or short distance advantages when striking time critical targets. They can also be positioned to reach targets that are further inland.
It is clear that the use of Land Attack missiles from submarines is not an aberration. Land attacks by submarines in the 1991 Gulf War (Dessert Storm) accounted for 4% of the total 288, with Tomahawk Land Attack Cruise Missiles fired, growing to 25% of the 450 used during the 1999 Kosovo War (Allied Force) to 33% of the 800+ fired during the 2003 Gulf War (Iraqi Freedom). Twelve US submarines and two British submarines were used in Iraqi freedom with more Tomahawks fired from submarines in the initial “shock and awe” phase than any other platform.
Whilst the use of submarine launched land attack missiles is clearly most advantageous during the opening stages of a campaign, it is noted that USS MIAMI did conduct time sensitive firings throughout the 1999 operation “Allied Force”.

Anti Shipping Operations

Once war has commenced, submarines can then conduct traditional interdiction and strike against enemy naval vessels and merchant ships.
Recent examples of submarines being employed in an anti-shipping role come from both the 1971 Indo-Pakistani War and the 1982 Falklands War.
On the evening of the 8th December, 1971, the Pakistani submarine PNS HANGOR was operating off the Rann of Kutch and sighted two Indian Naval frigates, the INS KIRPAN and the INS KHUKRI. PNS HANGOR closed and fired one unsuccessful torpedo at the INS KIRPAN before firing three homing torpedoes at INS KHUKRI. Two of the three shots were successful and the ship sunk with considerable loss of life (Donohue, 1989).
On 30 April 1982, while patrolling well south of the Falkland Island, the Argentinean cruiser GENERAL BELGRANO was detected by the British SSN, HMS CONQUEROR. The submarine approached her over the following day. At 15:57 on May 2, HMS CONQUEROR fired three straight running Mk 8 torpedoes at GENERAL BELGRANO, of which two struck. The ship quickly began listing to port and sinking by the bow. Twenty minutes after the attack at 16:24 Captain Bonzo ordered the crew to abandon ship. The ship sank with the loss of 323 lives.
Worthy of mention are the exploits of one Argentinean submarine in the same war. The ARA SAN LUIS departed for patrol in the second week of April 1982 and conducted one continuous patrol during the war. ARA SAN LUIS patrolled to the north of the Falklands and conducted attacks on British warships. On the 1st of May she attacked HMS BRILLIANT and HMS YARMOUTH unsuccessfully, with a weapon bouncing off the hull of one of the ships. ARA SAN LUIS was counter attacked for 20 hours with depth charges and one torpedo after the attack. On May the 10th she attacked HMS ARROW and HMS ALACRITY, although this attack was also unsuccessful. HMS ARROW’s towed countermeasures were damaged. Once again, the weapons did not perform as they should have. Although her endeavours were in vain on account of her torpedoes not arming, had these attacks been successful they may well have changed the outcome of the war.
Even the oldest of submarines can be quite effective at conducting anti-shipping operations. This is particularly true if the adversary lacks air and sea control and will therefore be restricted in their ability to conduct anti-submarine warfare (ASW) operations.
Likely targets for submarines are high value units such as aircraft carriers, cruisers, amphibious ships and replenishment ships.
Operations can be conducted against merchant shipping as well. Whilst attacking these vessels is a relatively simple operation from a tactical perspective it must be pointed out that the action is complicated by legal and political issues. It should also be noted that small modern day torpedo inventories might limit their usage against all but the most important of merchant targets.

Anti-Submarine Warfare

Anti-submarine warfare involves the locating and neutralizing of enemy submarines, or, if that is not possible, minimizing their effectiveness.
Whilst submariners tend to boast a submarine is the best ASW platform, the reality is that the passive detection ranges of modern submarines have decreased to under a kilometre. Other assets can have advantages over a submarine as an ASW platform due to their speed and geographic disposition. They can easily outperform a single submarine performing ASW.
Nonetheless, there are circumstances when a submarine may still be the best ASW option. Clearly they can be used to destroy submarines that have been trailed since leaving their ports. They can be effective in operations very close to enemy submarine bases, in choke points through which enemy submarine must pass or around one’s own naval bases or amphibious forces. Submarines can also be used to conduct ASW where environmental conditions, such as high seas or ice coverage, limit the use of other assets. Finally, it is acknowledged that submarines are one of the few platforms that can conduct ASW in areas when own forces lack sea and air control.
In wartime it is likely that a maritime commander would be reluctant to shift limited submarine resources from otherwise offensive activities with high probabilities of success to a defensive ASW activity with a low probability of success.

Other Wartime Tasks

Once hostilities have commences, submarines can still be employed to conduct ISR, REA, Special Forces insertion and support and mine laying.
They can also be used to conduct indications and warning operations. At the later stages of the Falklands War British submarine were deployed along the coast of Argentina near military airfields and used as early warning pickets, warning other fleet units of aircraft approaching the task group and the islands.
Submarines can be used to conduct cargo operations, although this is generally not considered an effective use of a submarine asset unless the cargo is part of a covert or clandestine operation.


Submarines are a powerful offensive weapon in war. They have the ability to project power into the heart of an enemy’s territory. They are an essential component of any nation’s war machine.
Having covered generic peacetime and wartime roles for submarines, next month we will explore their use in the Australian context such that we can start to gain an appreciation for what type of submarine capability might best suit our needs.


APDR at a glance