Singapore's Leopard 2A4 And The Great German Panzer Sale

 

 

 

Polish Leopard 2A4. Poland bought 128 Leopard 2A4 MBT
through the Great Panzer Sale in the mid-2000s.  Photo via Wikicommons.

A Brief History of the Tank : From Mark I to Leopard 2

The tank is a tracked, armoured fighting vehicle which was first used by the British during World War One. The year was 1916 and WWI had dragged into its third year. On the high seas, the Royal Navy has had some strategic success at the Battle of Jutland against the German Navy, though the threat of unrestricted submarine warfare was about to begin. On the aerial front, the Fokker Scourge which started in the previous year was largely over, thanks to the deployment of better Allied fighters and tactics. On land however, the initially dynamic nature of land combat had deteriorated into a stalemate of trench warfare, where barb wires, artillery and machine guns prevented any real advancement for both the Allied Armies and the German Army. Soldiers died by the thousands when attempting to cross no man's land between the opposing forces.

 

The World's first combat tank : The British Mark I " Male " Tank
with two 6 Pounder Guns at the Battle of the Somme 25th Sep 1916.
Photo : Imperial War Museum via Wikipaedia

 

 

 

In order to break this deadlock, the British Army introduced an armoured vehicle at the Battle of the Somme in Northern France. This tracked vehicle was supposed to be able to traverse over trenches and provide protection against small arms and shrapnel for its crew and the infantry that followed it behind. It was armed with machine guns and modified naval guns. To conceal its true identity as a new weapon from the Germans, it was designated as a special water carrier ( as in water tank ) and the name stuck.

Though the British were the first to deploy tanks, it was the Germans who perfected the art of armoured warfare in the next great war - World War Two. Then, the German panzers ( tanks ) played a crucial role in the Blitzkrieg or lightning war that saw tanks spearheading offensive ground campaigns. Large scale battles were fought in the deserts of North Africa and the Steppes of Russia. Throughout the war the German panzer evolved from the 5 tonne light tank to culminate in the 68 tonne monster Tiger II main battle tank ( MBT ). These fortunately did not come in sufficient numbers to alter the course of the war for the German Army.

 

 

Leopard 1 Main Battle Tank

Hellenic Army Leopard 1A5 in a 2009 photo. Wikicommons.

 

Following WWII, the West German Army deployed the M-47 and M-48 Patton medium tanks supplied by the United States of America. These were post WWII designs and were obsolete by the late fifties and a replacement was urgently needed to guard the flat plains of Germany from the armoured might of the Warsaw Pact lead by the Soviets. This modern tank design was supposed to weigh no more than 30 tonnes and must protect the crew from nuclear fallout and chemical contamination. Its main armament was to consist of a 105mm main gun, the NATO standard at the time. Attempts to produce a Euro-panzer with France and Italy failed and eventually the West German Army fielded the final design as the Leopard 1 MBT and series production began in 1965. A total of 6485 Leopard 1 tanks have been produced so far, including utility and anti-aircraft variants. They serve in the armies of 12 countries including Canada and Denmark.

 

Leopard 2A4 MBT with its characteristic vertically-faced turret armour
Photo Source : Krauss-Maffei Wegmann GmbH

 

The Leopard 2 Main Battle Tank

Austrian Leopard 2A4 in 2011. Photo : Wikicommons

Austrian Leopard 2A4 in 2011. Photo : Wikicommons

 

The Leopard 2 MBT started life in 1970 after the failed US-German MBT-70 collaboration. Lessons learnt from the 1973 Yom Kippur War meant that the use of space armour for better crew protection was needed and a bigger gun to match the 125mm smooth-bore gun of the Warsaw Pact was required. To accommodate these changes, the Leopard 2 was to be significantly heavier than the Leopard 1. An early prototype, the Leopard 2 Austere Version, was pitted against the M-1 Abrams prototype ( then called the XM-1 ) at the Aberdeen Proving Grounds of Maryland, USA and showed that the Leopard 2 AV was in many ways on par with the XM-1. It finally entered service with the German Army in 1979, at the height of the Cold War between NATO and the Warsaw Pact. Eventually, more than 3480 would be produced in several variants serving in countries including the Netherlands, Sweden and Switzerland.

 

The Reunification of East and West Germany and The End of the Cold War

Following the collapse of the Berlin Wall in 1989, the German reunification was formally concluded in 1990 and the end of the Cold War came shortly after. Suddenly many NATO ( and Warsaw Pact ) countries found that their arch enemies had disappeared almost overnight and found it difficult to justify the maintenance of huge military capabilities. Defense budgets had been slashed drastically and personnel had been demobilised across Europe.

The German Armed Forces suddenly found itself inundated with Eastern Bloc hardware ( inherited from the merger with the East German Armed Forces ) like the MiG 29 Fulcrum air superiority fighters and must have found it logistically difficult to integrate them with their existing hardware. The Fulcrum fleet was ultimately given to the Polish Air Force for a token one Euro a piece!

The post Cold War German Army was to be reduced to only a fraction of its former glory. Adopted in 2007, the Structure 2010 initiative will cut the number of main battle tanks from 2528 to only 350. The number of infantry fighting vehicles from 2077 to 410 and artillery from 1055 to 120. This generated lots of surplus advance land fighting hardware which could only benefit Germany's trusted allies as they were sold off at rock bottom prices in what was popularly known as the Great German Tank Fire Sale ( der grosse Deutsche Panzer Schlussverkauf ).





Leopard 2A6EX MBT. Note the angled turret armour and the longer L55 120mm
smoothbore gun. Photo : Krauss-Maffei Wegmann

 

As Germany retains its late variant Leopard 2s ( mainly the Leopard 2A5 and the 2A6s ), the older and comparatively less capable 2A4s are sold to countries like Chile, Singapore, Poland and Turkey, probably at less than a million dollar (USD) each. A new US or Western European main battle tank would probably set you back by USD 5 million a piece. So a second hand Kampfpanzer Leopard 2A4 represents an estimated 80% savings compared with buying new! This represented a unique opportunity for many countries to upgrade their MBT fleet to ultra-modern standards without incurring a huge fee. It has been said that at such fire sale prices, even less capable MBTs like the Russian T-72 and its derivatives do not make sense. It is prudent and shrewd purchases like these that help to limit Singapore's annual defense spending to be leveled at around 4.5% of GDP throughout recent years, although the Singapore government is prepared to spend up to 6% of GDP on defense.

 

The Armoured Fist of the Singapore Armed Forces

The Singapore Armed Forces operated a fleet of some 350 French AMX-13 light tanks spotting 75mm guns. These were originally designed to be air-portable for supporting paratroop operations. They have been in service with the Singapore Army since 1969 and had been extensively refurbished to the so called AMX-13 SM-1 standard by ST Kinetics, a local defence company back in 1988. They have more or less served their purpose over the past 40 years and have almost reached their end-of-life / end-of-type. It is the ageing AMX-13s that the Leopard 2A4 was supposed to replace, at least that was the official announcement by the MoD. However, although it has never been officially acknowledged, reports are rife that SAF had been operating the British made Centurion MBT for many years out of foreign bases. According to Wikipedia, Singapore had acquired a total of 63 Centurion Mk3 and Mk7 from India in 1975 and subsequently from Israel in 1993 & 94 as well. They have been upgraded with new guns and engines with the help of the Israelis and are known as the Tempest MBT.
 

The SAF was once the top operator by number of the French made AMX-13 light tank. Photo SAF

 

In acquiring the Leopard 2A4, the SAF gains a huge capability boost in a value for money deal. An initial 66 Leopard 2A4s were bought together with 30 as spares, and subsequently 36 more were added. These 102 Leopards will form the backbone of the 48 SAR ( 48th Battalion, Singapore Armoured Regiment ) based at Sungei Gedong Camp.

The 2A4s lack the up-armoured sloping turrets commonly seen in more advanced versions like the 2A5 and also sports a shorter version of the 120mm main gun but are still potent main battle tanks nonetheless.

Leopard 2A5 with angled arrow-shaped applique armour
 of the Bundeswehr maneuvering in 2010. Photo : Wikipedia

Here is a glance of the Leopard 2A4's characteristics and capabilities :

• Weight : 55 Tonnes
• Crew : 4
• Main Gun : Rheinmetall L44 120mm smoothbore gun
• Ammunition : DM-33KE ( APFSDS-T ) or DM-12 MZ ( HEAT-MP-T )
• Secondary Armament : 7.62mm Co-axial Machine Gun
• Secondary Armament : 7.62mm Anti-aircraft Machine Gun
• Smoke Launchers : 16 76mm Smoke Launchers
• Gun Control System : Fully Stabilised in Alt-Azimuth / Thermal Imager / Laser Range Finder
• Communications : Digital Radio / Networking Capabilities
• Armour : Spaced multi-layered Armour

High Explosive Anti-Tank Multi-Purpose (HEAT-MP ) are chemical energy rounds that utilise the chemical energy in explosives to form a penetrative jet of molten metal directed at the armour at hypersonic speeds.

Armour Piercing Fin Stabilised Discarding Sabot ( APFSDS ) are kinetic energy rounds that depend on the high velocity of a metal rod penetrator to punch through armour. DU or depleted uranium, with its high density, is commonly used to manufacture APFSDS penetrator rods. However, all German APFSDS round are non-DU, frequently using monobloc tungsten instead.

Loading the distinctively shaped anti-tank sabot rounds ( APFSDS )
onto a Leopard 2SG at Shoalwater Bay, Queensland, Australia,
 during Ex Wallaby 2015. Photo : SAF

Main Battle Tanks of Regional Countries

In April 2003 Malaysia signed a deal worth USD 375 million to purchase 48 PT-91M MBT from Poland. The package also includes 6 WZT-4 ARVs or armoured recovery vehicles, 5 PMC Leguan armoured vehicle-launched bridge, 3 MID-M engineering tanks and 1 SJ-09 driver training tank. These PT-91M "Pendekar" are new builds of extensively modernised Cold War Era Soviet T-72M1 MBT. They equip the 11th Regiment of the Royal Armoured Corps based in Gemas, a small town in the State of Negeri Sembilan in Peninsular Malaysia. It has a 125mm smoothbore gun, a dual-axis stabilised fire control system, composite armour, explosive reactive armour, laser warning system, upgraded engines and the works. If you do the sums, each tank cost about USD 6 million, maybe more when other "hidden costs", so commonly encountered in that country, are taken into consideration. At the end of the day, a modernised T-72 is still, a T-72! It is considered by many to be inferior to the Leopard 2.

Polish PT-91 Twardy from which Malaysia's PT-91M was derived in a 2009 Photo. Wikipedia.

According to Wikipedia, Thailand has 105 M-48 and 178 M-60A1 / A3 MBT. They are excellent for intimidating the civilians and for patrolling or blockading the streets as and when the need so frequently arises in Thailand. It had also acquired 300 Chinese Type 69II MBT in the 1990s. The Type 69s are basically Chinese upgraded versions of the Soviet T-55 MBT. They are reputed to be unreliable and of such poor quality that the Royal Thai Army had largely assigned them for training purposes or just put into storage. In 2011, an order for 49 Ukrainian T-84 Oplot-M MBT had been placed and up to 200 might be eventually procured. A small order for Chinese VT-4 MBT had also been placed with deliveries due end 2016.

Royal Thai Army M-60A1 MBT during Cobra Gold 2014. Photo : Wikipaedia

Indonesia was a late comer to the Panzer Fire Sale receiving their first Leopard 2A4s in Sep 2013. A total of 103 Leopard 2A4 had been taken up together with 4 Armour Recovery Vehicles, 3 Bridge Laying Tanks and 3 Armoured Engineering Vehicles for an estimated USD 287 million. A number of the 2A4s will be upgraded to the Leopard 2 Revolution standard by Rheinmetall.

Panzerschnellbrücke Leguan bridge laying tank based on the Leopard 2 chassis

The Australian Army used to deploy the Leopard AS1 MBT ( 1A4 ). In March 2004, the decision to purchase 59 US M1A1 Abrams MBT to replace the ageing Leopard AS1s was finalised. Deliveries were completed in 2007. 18 are based in Victoria where the School of Armour is and the rest, 41 in total, will be base in Darwin, Northern Territories. The M1A1 shares the same origins as the Leopard 2 ( the failed MBT-70 project ) and even mounts the same Rheinmetall 120mm smoothbore gun. It uses steel encased depleted uranium armour that has been said to deflect / bounce off Iraqi T-72 rounds fired at a range of 1000m during the last Gulf War. It is a formidable platform, even though it is not the latest M1A2 variant.

Australian Army Leopard AS1 ( 1A4 ) at
 Shoalwater Bay Training Area 2005. Wikipaedia

Australian Army M1A1 Abrams at Shoalwater Bay
Training Area during Talisman Sabre 2011. Wikipaedia

Future MBTs for Singapore's Armoured Forces

The Great German Tank Fire Sale was a once in a lifetime event unlikely to be repeated, too good an opportunity to be missed for many of Germany's allies to upgrade their armoured fleets. Germany stands to gain too, from the refurbishment contracts that are frequently awarded to German companies and from the training packages provided to foreign army personnel.

Perhaps in future, these Leopard 2A4s can be upgraded to the 2A6M standard, with a longer L55 gun that have a longer range and increased armour penetration, better armour and better protection against mines and improvised explosive devices ( IED ). The Canadian experience in Afghanistan clearly showed the importance of having mine protected MBT. The LAV III / Stryker Infantry Fighting Vehicles simply did not have the cross-country ability of the MBTs and nor the level of protection against IEDs and land mines. In Nov 2007 one of the Canadian ex-Bundeswehr Leopard 2A6M-CAN was attacked by the Taliban with a large booby trap / IED. The tank was damaged but the entire crew survived. The tank has since been repaired and was back in operations.

Krauss-Maffei Wegmann GmbH has also fielded a Leopard 2A6 PSO ( Peace Support Operations ) prototype for urban warfare. It has more effective all-around protection, better reconnaissance capabilities, non-lethal armaments, close-range surveillance capabilities through camera systems, a secondary weapons station ( remotely controlled ), a bulldozer blade, search lights and a shorter gun barrel ( obvious reasons ). This is similar to the M1A2 TUSK ( Tank Urban Survival Kit ) upgrade of the US Army. With SAF increasingly participating in international peace keeping operations and the highly urbanised city environment of Singapore, this PSO version may make sense.

Even further ahead, SAF may well develop its own unmanned ground vehicle. Time will tell.




Since 2010, Singapore's Leopard 2A4 MBTs had been upgraded
and are now known as the Leopard 2SG, seen here at
 the 3rd Division change of command ceremony 2016. Photo : SAF

 

 

AIP Submarines For RSN



The New Archer-Class ( ex-Vastergotland Class ) Submarine



HMS Sodermanland was a Vastergotland-class SSK that was upgraded in 2003 with AIP.
Seen here in a 2010 photo. Photo via Wikicommons




In case you do not know, RSN stands for the Republic of Singapore Navy. The RSN has been operating submarines since 1995, when a total of 5 ex-Swedish Navy A-11 Sjöormen Class SSKs ( Diesel-electric Attack Submarines ) were acquired when they were being retired by the Swedes. These old boats were all launched between the years 1967 to 1968 making them more than 25 years old when they were sold to Singapore.

However, they were extensively refurbished and modernised by Kockums AB of Sweden ( now SAAB as of 2015 ) for operations in tropical climate before being re-commissioned for the RSN as the RSS Challenger Class submarines. Four of these boats form the backbone of the 171 Squadron while the fifth boat is cannabilised for spares.

The RSN subsequently acquired another 2 submarines from Sweden in late 2005, the A-17 Vastergotland Class SSK, which had been retired from service by the RSwN ( Royal Swedish Navy ). Again, Kockums AB was engaged to refurbish these submarines. At that time little else was announced about the deal, especially whether the refurbished boats will have Air-Independent Propulsion (AIP) technology*. Today, 16th Jun 2009, the public learnt from the daily newspapers and MINDEF releases that these two boats are the RSS Archer and RSS Swordsman. RSS Archer has been launched at Kockums AB yard at Karlskrona by Mrs Teo Chee Hian, wife of the DPM / Minister for Defense.

Swedish newspapers reported that the Vastergotland deal was worth SEK 1 billion, then equivalent to US$135 million.
 



Launch of the RSS Archer at Kockums Shipyard in Karlskrona 16th Jun 2009.
Photosource : Kockums AB Photographer : Peter Nilsson 

What is Air Independent Propulsion?

AIP is simply a non-nuclear submarine propulsion system that works without requiring an external supply of air. It allows a conventional ( non-nuclear ) submarine to remain submerged for a longer period of time compared with their diesel-electric cousins as the AIP engine negates the need for an external supply of air / oxygen.

 

Diesel-electric submarines have batteries that need to be recharged by their diesel engines every now and then when they are depleted. Running the diesel engines require air / oxygen that can only be supplied when the submarine is either on the surface or when it is snorkeling. When snorkeling, the submarine stays submerged just beneath the surface but sticks its snorkel mast up to suck in air and expel diesel exhaust.

These activities put the submarine at increased risk of being detected by visual or infra-red sighting, radar reflection from the snorkeling mast or conning tower, magnetic anomaly disturbances or by the acoustic signature of the noisy diesel engines.

With AIP, all of the above risks normally associated with battery recharging will be eliminated. It allows the submarine to remain submerged for 2 weeks or more and makes the AIP submarine much stealthier than its diesel-electric counterpart.

The AIP Integrator

Kockums AB is the Swedish shipyard owned by Germany's ThyssenKrupp Marine Systems after a series of mergers and acquisitions starting from 1999. They have been building quality submarines for Sweden since 1912 and were the first in the world to produce a purpose-built AIP submarine the A-19 Gotland-class. While the RSwN retired the HMS Vastergotland and her sister ship HMS Halsingland, it chose to upgrade the newer two ships, the HMS Sodermanland and the HMS Ostergotland to being AIP capable using Kockum AB's proprietary AIP Stirling Engine. Kockums basically cut the submarines into two at mid section and lengthened the hull to accommodate the new Stirling Engine. The Stirling AIP uses diesel and oxygen in a closed system. The upgrade is so radical that the 2 boats are considered a new class of their own - the Sodermanland Class.

 

 

Royal Swedish Navy : All AIP Fleet

 

With the completion of the Sodermanland-class upgrade, the Royal Swedish Navy became the only navy in the world to have an entirely AIP capable submarine fleet. Nobody else could have that claim. Who else better to turn to when you need AIP submarines than the Swedes? They are the experts!

The A17 HMS Vastergotland ( left ) and the more advanced
A19 Gotland-class HMS Uppland  along side at Malmo, Sweden.
Photo taken in 2003 before the Vastergotland was sold to Singapore. Wikicommons



HMS Sodermanland and the submarine rescue ship A-214 HMS Belos in 2003. Wikicommons

 

Blue Water vs Brown Water

The US Navy commissioned the world's first operational nuclear submarine the USS Nautilus (SSN-571) in 1954 and never looked back. Their last batch of conventional diesel-electric submarine, the Barbel-class, was ordered between 1955 to 1956 and all had been retired by 1990. They now have an exclusively nuclear underwater fleet which is extremely effective for blue water ( open ocean ) operations which require long endurances. The Swedes however, have vastly different requirements where they have huge swaths of coastlines with deep narrow fjords to patrol. The salinity and temperature of the Baltic Sea are also very different from that of the open oceans and therefore the Swedes have long settled with conventionally powered submarines.
 

Singapore is a littoral state with plenty of shallow, murky waters and busy, noisy sea lanes. The small Swedish SSKs are well suited for this kind of underwater environment. Besides, modern diesel-electric submarines, like the Russian Type 636 improved Kilo Class SSK, can be extremely quiet especially when they are drifting or moving very slowly ( less than 5 Knots ). In fact, the RSwN HMS Gotland was "leased" to the USN for 2 years between 2005 to 2007, complete with crew, for bilateral anti-submarine exercises. Uncle Sam will not need to practice ASW with HMS Gotland if it was not quiet!

Growth of RSN's ASW Capabilities

The Anti-Submarine Warfare (ASW) capabilities of the RSN has grown in leaps and bounds ever since its early days of operating the Seawolf-class missile gunboats ( since retired ). In the 80s came the Victory Class missile corvettes with their variable depth sonar and Whitehead Alenia torpedoes. The 90s saw the addition of the Fearless Class ASW Patrol Vessels and of course, the best ASW platform, the Challenger Class SSKs.
The missile corvettes and the patrol vessels are both too small to accommodate any ASW helicopters. That glaring deficiency has since been rectified with the purchase of the Formidable Class stealth frigates which will carry the Sikorsky S70B Seahawk ASW helicopter, assumingly with magnetic anomaly detectors and towed array sonars plus offensive weapons like the mk46 torpedoes.
With the commissioning of the RSS Archer and Swordsman due in ?2010/2011, the RSN will have AIP technology among its submarine fleet and significantly increase its reach.
We must also not forget the aerial assets of the RSN, the Fokker F50 maritime patrol aircraft, in operation with the 121 Squadron since 1993, which acts as a force multiplier when dealing with naval threats.




What Singapore's Neighbours Have or Are Acquiring

The Malaysians have received their first of 2 Scorpene Class SSK earlier this year, the KD Tunku Abdul Rahman. These Scorpenes are not AIP endowed, unlike their more capable Spanish S-80 / S-80A cousins with the MESMA AIP engine which uses ethanol and compressed oxygen. They have another older Agosta B SSK based in France for training purposes. Since these were bought in 2002 during Malaysia's M-Era, the officially stated RM3.4billion package came with certain landing rights at the Charles de Gulle Airport for MAS as well. Maybe they could have had 3 scorpenes for the same price ( or 2 scorpene basic-AIPs ) had they not insisted on those landing rights, or having to pay the hundred over million ringgit of brokerage fees, or.... I digress. The second boat KD Tun Razak is due to be commissioned later this year.

The Indonesians have 2 ageing Type 209 / 1300 Cakra Class SSK since 1981. They have been recently upgraded by the South Koreans who also operate the Type 206 / Type 209 submarine. The Type 209 is one of the most widely exported submarine from the West. They have made an agreement with Putin in 2007 to buy among other things, 2 Type 636 Kilo Class SSK plus options for another 8 more. These orders have yet to be fulfilled.

Thailand has no submarine fleet but are eager to acquire one. Earlier efforts by Sweden to sell them the A19 Gotland Class submarine have failed to materialise. Most of the money could have gone into financing their purchase of the 12 SAAB JAS-39 Gripen fighters and the 2 SAAB S-1000 Erieye AEW. Air Force 1 Navy 0.

Vietnam has 2 ex-Yugoslav minisubs for special forces operations and has recently ( Apr 09 ) agreed in principle to buy 6 Russian Type 636 Kilo Class SSK. Pegged at USD1.8Billion these are said to be originally the ones ordered by Venezuela, but with Hugo Chavez's falling oil fortunes are now going to Vietnam.

Australia has 6 Type 471 Collins Class Diesel-electric SSK designed by Kockums AB. These are among the world's largest non-nuclear submarines displacing 3350tons submerged suited to patrolling the vast coastlines of Australia. They are quiet and capable boats with a large weapons load including the Boeing Sub-Harpoon anti-ship missile and the Mk48 ADCAP torpedoes. They can be retrofitted with AIP engines. Following a bad start with lots of delays and deficiencies, these boats have been upgraded with a combat control system from Raytheon similar to the one in the Virginia Class SSN of the US Navy.

The New Zealanders are on good terms with the Aussies and do not have any perceived threats in their immediate vicinity. The Helen Clarke Government retired the last of their 1950 era McDonnell Douglas A-4Ks without any replacement. Their air force now only operates helicopters and transports. The RNZN does not own any submarines.

The Future

What next after the RSS Archer? The RSN will probably retire part of its Challenger Class fleet upon arrival of the RSS Archer and RSS Swordsman. They can be mothballed or be used as a training submarine or be cannibalized for spare parts. Once its AIP operational experience has been gained, it can either look to acquire the A-19 Gotland Class when the Swedes are ready to retire them or consider other advanced options like the German HDW U212 / U214 AIP SSKs or the Russian Amur 1650 / Amur 950 / Kilo SSKs or God forbid, the DCNS / Navantia Scorpene SSK.

Update 2013

RSS Archer and Swordsman have both been commissioned. The 4 older Challenger Class submarines are still operational. There are now rumours that RSN could be interested in the latest Swedish A26 Class submarine.

The Collins Class SSKs of Australia is still plagued by generator and sonar problems. Only one out of six ship is currently operational. The RAN is looking to acquire 12 new enhanced-Collins type submarines as their replacement.

Indonesia bought 3 Type 209 / 1400s from South Korea.

Malaysia has received Exocet missiles with land attack capabilities for their Scorpene submarines, range about 180km .....

Update 3rd Dec 2013

In the Straits Times : The Republic of Singapore Navy will be acquiring 2 customized Type 218SG AIP submarines from HDW Kiel. They are likely to be ready by 2020. Two of the older Challenger class non-AIP submarines will be retired.