How would the REİS-Class Submarines Affect the Power Balance the East-Med and the Aegean Sea?


Issue 105

The physical conditions of naval warfare provide inherent advantages to submarines, making it extremely challenging to fight this invisible element. Although countries try to create new tactics by supporting their navies with sophisticated solutions with technology advancement, submarines still have a significant advantage over surface assets.

It is quite challenging to fight against submarines. Because it is tough for the sonar signals to reach beyond the “layer-depth”, which is formed according to daily water conditions. The layer-depth reflects the incoming sound waves, so when a submarine that submerges below the layer-depth becomes almost undetectable from a safe distance with hull-mounted sonars. Therefore, Navies try to penetrate this layer by using sonobuoys (launched from Maritime Patrol Aircraft), towed array sonars, variable depth sonars (towed by ships), and dipping sonars (deployed by helicopters). However, trying to locate a sub in large areas such as the Eastern Mediterranean is like looking for a needle in a haystack. Furthermore, the sonar interference created by the underwater noise in shallow waters such as the Aegean Sea, with a challenging topography for naval warfare, makes it harder to cope with submarines in these waters.

Due to these roughly explained issues, the existence of submarines, regardless of type, is a significant parameter that changes the regional balances on its own. As the silent hunters of the seas, their unique capabilities such as sinking a ship with a single torpedo, collecting intelligence of critical locations such as coastal batteries and radar facilities undetected, infiltrating behind enemy lines, and reporting valuable target information to strike platforms, as well as altering the course of the war by attacking enemy shores and breaking the enemy's will to fight, makes submarines "strategic" assets, unlike other naval warfare elements. 

Therefore, submarines movements are considered as one of the most significant parameters for understanding the level and severity of the tensions in the seas. If one of two countries in conflict sends its submarines to the disputed area, this situation is interpreted as that country considers all options, including war. For example, Russia's Baltic Fleet sent ten submarines to the Norwegian Sea on 28 October 2019 to respond to NATO's activities in the Baltic Sea. This incident caused great anxiety in NATO and Baltic countries. That is how important the existence and capabilities of submarines are.

Submarines have taken their place in history as the elements that changed the fate of the war. For example, the sinking of Argentine Navy light cruiser ARA General Belgrano (C-4) by the nuclear-powered Royal Navy submarine HMS Conqueror (S48) during the Falkland War on May 2, 1982, forced the Argentine Navy to stay outside the planned operational area and changed the course of the war.

Air Independent Propulsion (AIP) Submarines

Submarines are generally classified with their main propulsion systems and the strategic missiles they carry. Also known as classical submarines, the basic submarine type Diesel-electric submarines (SSK) have been used by many countries for decades. Despite the advantage of the silence underwater, these submarines are routinely required to return to periscope depth and perform snorkeling to charge their batteries periodically. This process diminishes the tactical elasticity of diesel submarines and makes them vulnerable to detection and engagement. 

Another type, nuclear submarines (SSN), are larger and more sophisticated, and their size allows them to carry numerous strategic missiles. Despite these advantages, both the nuclear reactor and other operating systems' noise causes a disadvantage for nuclear submarines, especially at submarine-to-submarine combat.

Developed as a new type to overcome the other two types' disadvantages, Air Independent Propulsion (AIP) submarines are considered one of today's balance-changing parameters. These vessels are both silent and can stay submerged for prolonged periods. Although the air-independent propulsion systems were implemented with the closed diesel cycle and Swedish origin Stirling type engines in the 20th century, they did not have a wide range of use in the beginning. However, mainly thanks to the German-Italian co-production Type 212 submarines, which were developed with the German origin fuel cell technology, and later the Type 214 class submarines acquired by South Korea, Greece, Portugal, and Turkey, the AIP submarines took their place in the seas. 

AIP submarines are superior to diesel submarines. The most important reason for this superiority is that diesel-powered subs need to return to periscope depth and perform snorkeling at least every 24 hours, while AIP submarines can stay submerged for weeks. Conventional submarines need off-schedule snorkeling because their battery is emptied before the planned schedule if it exceeds the standard patrol speed while underwater. This situation is especially true in scenarios where the opposing forces conduct dense Anti-Submarine Warfare (ASW) activities. Thus, it is quite difficult for diesel-electric submarines to escape if ASW assets somehow acquire contact with the submarine. However, if AIP submarines encounter hostile ASW elements somehow, they can quickly descend below the layer-depth and escape through the opposite route. The AIP subs’ capability to escape from ASW units in this way will widen the uncertainty area to be searched and cause the opponent to make more effort to find it. 

Since AIP submarines rarely surface or return to periscope depth, they are less to be mentioned in intelligence reports, which are the most critical instrument for finding and tracking submarines. Because of their capability to cross the Mediterranean from one end to the other submerged, even if these submarines do not sail, their presence alone is a vital criterion for the enemy to take into consideration. A naval force that knows there is an AIP submarine in its area of interest will have to engage in intense ASW activity before moving its high-value units (HVU) through choke points, even if it does not have any intelligence about the sub or made contact previously. For sure, this extra effort will significantly disrupt its planned operations and cause a delay.

The reactors of nuclear submarines and the transmission system that transfers the energy generated by the reactor to the sub's propellers create much more noise than it should be for a submarine. Therefore, diesel submarines' popularity does not diminish, although they have limited maneuverability and weapon capacity comparing with the SSNs. Additionally, this situation makes it difficult for nuclear submarines to detect diesel submarines, but the noise created by the routine snorkeling of diesel submarines occasionally reduces this advantage. Since AIP submarines do not need snorkeling, they can fight nuclear submarines underwater for weeks and attack them without being detected. 

In addition to these advantages, AIP diesel submarines gained new features in recent years, such as guiding multiple torpedoes simultaneously, launching ballistic and nuclear missiles, satellite communication (SatCom), network-centric warfare, and mine laying capability, which make the AIP submarines a prominent force multiplier in naval warfare.

Can REİS-Class Subs Change the Maritime Balance?

The Reis-Class submarines (Type 214TN), the first of which was launched in December 2019, are considered a capability that will significantly change the balance in Turkey’s surrounding seas. Six of these submarines with a length of 68 meters and a displacement of around 2000 tons will be built for the Turkish Navy. These submarines are planned to be commissioned between 2022-2027. Indigenous weapons such as AKYA Heavyweight Torpedo are also expected to be fitted to these submarines, intended to have domestic solutions for various subsystems. Although it is not included in the current architecture designed by the manufacturer ThyssenKrupp Marine Systems, the following ships of the Reis-Class submarines, which will be equipped with missiles such as Harpoon Block-II with coastal attack capability, is also expected to be capable of launching Gezgin cruise missile. 

As the equivalent of Reis-Class Submarines in the Eastern Mediterranean region, Greece currently has 4 Type 214 AIP submarines and 1 Type 209 AIP modernized submarine in its inventory. Israel actively operates 2 Dolphin-II class AIP submarines. In the coming years, Israel plans to increase the number of AIP to 6. Other countries in the region (e.g., Syria, Egypt, Algeria) do not have submarines with AIP technology yet.

In addition to 6 REİS-class subs, commissioning national submarines to be produced under the MİLDEN project, which is currently in the design phase, will make a significant difference in the region. Implementing various capabilities of the technologically advanced GÜR class submarines to some of the older AY and PREVEZE class submarines under the MÜREN project will reinforce the distinguished position of the Turkish Navy's Submarine Fleet among the Mediterranean Navies.

Like Turkey's other accomplishments in the defense industry in the last quarter-century, Turkey's balance-changing acquisition of AIP submarines is closely followed by both the countries of the region and the global players. The increased presence of the Turkish Navy in the surrounding seas, especially after the Blue Homeland doctrine's physical implementation, gives a vital clue about how actively the Reis-Class submarines will be used after they entered service.

Greece had to considerably cut its defense expenditure and froze its defense industry projects due to the great economic crisis in 2008, which reduced the Greek Navy's effectiveness in the Aegean Sea. Facing the increasing force of the Turkish Navy in this process, Greece sees AIP submarines as a critical advantage, apart from the geographical advantage of the islands. Therefore, it does not want Turkey to acquire this technology. In this context, Greece has increased its diplomatic initiatives in the European Union due to the Oruç Reis seismic research ship's activities in the Eastern Mediterranean, and Greek Foreign Minister Nikos Dendias urged Germany to withdraw its support for the Reis-Class submarine project on September 11, 2020. In this statement, Dendias expressed his concern that Greece's self-proclaimed strategic advantage in the Southeast Mediterranean and the Aegean Sea might be diminished.

Israel, whose defense doctrine is based on protecting its mainland, and the Leviathan & Tamar oil platforms, has different expectations from AIP submarines. Israel awaits its threat will mostly come from Iran and the armed groups it supports. In this context, Israel aims to reinforce the advanced air defense systems in its mainland with Barak-8 long-range air defense missiles onboard the Sa'ar 6 class corvettes recently purchased. Therefore, Israel can use its highly technological AIP submarines to counter possible underwater threats against the mainland and respond with strategic missiles on their subs in case of an attack. Israel could deploy these submarines in the Persian Gulf without being detected and strike Iran's critical facilities with cruise or nuclear missiles. As it can be understood from here, Israel's primary advantage over Iran and its neighboring countries is the superiority of its air force and Dolphin-II class submarines' capability to hit strategic targets deep inside the opponent's territory.

After the commissioning of REİS-Class submarines, the Turkish Naval Forces will have the highest number of AIP submarines in the Aegean Sea and the Eastern Mediterranean, and the only instrument that Greece considers as an advantage will disappear. Although islands provide considerable geographical advantages, they also need adequate protection. Therefore, if Greece dares to increase its territorial waters to 12 nautical miles, which is considered as 'Casus Belli' (the occasion for war) by Turkey, the Turkish Navy's AIP submarines operating in the territorial waters of Greek islands without being detected for days will pose a serious threat and change the balance in favor of Turkey. While Turkey covers the area of interest with its AIP capable submarines and UAVs/UCAVs, which have been very successful in Libya, Syria, and Azerbaijan, they will be able to provide Anti Access/Area Denial (A2/AD) without the intense presence of the surface assets.

Even though it is generally thought that Israel will use its AIP submarines first and foremost based on its long-standing threat perception, Turkey's lack of AIP submarines provided an edge to the Greek- Israeli side in the Eastern Mediterranean, which started as a natural gas consortium and then turned into a military alliance in recent years. However, the political and military power of a possible coalition between Israel, Greece, and Egypt in the Eastern Mediterranean will be shaken with the commissioning of Reis-Class and MİLDEN submarines, and the Turkish Naval Forces will have the upper hand. The uninterrupted patrol that these submarines will establish in critical passages in the region while staying hidden underwater will cut the Aegean-Mediterranean-Cyprus maritime transportation that Greece will need in case of a possible crisis in the region and may prevent the transfer of strategic forces. Moreover, these submarines will also give vital information to the surface units that will serve in the Aegean Sea under the protection of the UCAVs and S-400 air defense system that may be deployed in the region, which will provide significant advantages in generating the Recognized Maritime Picture (RMP) in times of crisis and making effective engagements in case of aggression. 

The AIP submarines, which will become the silent and effective underwater members of the network-centric warfare with their satellite communication and Link-11 capabilities, will change the military balance in both the Aegean Sea and the Eastern Mediterranean. Furthermore, they will provide significant target intelligence together with our military satellites by conducting intelligence missions in peacetime.

Consequently, while Turkey will weaken the influence of the coalition formed against it in the Aegean Sea and the Eastern Mediterranean politically thanks to the additional tactical elasticity and combat capabilities of the AIP submarines, it will also successfully establish underwater protection at the tactical level similar to the air protection provided by the S-400s. The impact of the submarine strength of the Turkish Naval Forces, which is effective, deterrent, and respected in maintaining peace, will be felt by all the countries in the region and will be a significant milestone for protecting our interests in the Blue Homeland.