The Sejong Daewang-class destroyer, also known as the Sejong the Great-class or the KDX-III
class, is one of the most important naval assets in the Asia Pacific Region.
The Republic of Korea Navy, shortly ROKN, which already has three vessels in this class,
launched the fourth one in July 2022.
The fifth and sixth vessels are on the way.
As the Weapon Detective, we are now investigating the Sejong Daewang-class, the South Korean
Aegis destroyer.
The Sejong Daewang-class destroyers are the largest and most combat-capable surface combatants
of the ROKN.
They are even superior to their Chinese and Japanese counterparts in these areas.
Analysing this warship can give us many clues about South Korean national security concerns
and the regional military balance.
Until commissioning the Fletcher-class destroyers in the 1960s, the ROKN was a coastal naval
force.
By the late 1970s, the South Korean industrial capabilities and the economy boomed, and keeping
the sea lines open became more crucial for Seoul.
Thus, the President of South Korea, Park Chung-hee, introduced an eight-year plan to establish
a self-contained national defence force, under which the domestic naval shipbuilding programme
also began.
The first examples of this ambitious aim were the Pohang-class corvette and Ulsan-class
frigate.
With confidence based on these successful projects, South Korea began to work on destroyer-size
surface combatants in the early 1990s under the KDX Programme.
The first step of this programme was the Gwanggaeto Daewang-class, also known as KDX I-class,
vessels.
Due to the crisis around Dokdo in 1997, Seoul decided to increase the ROKN's blue water
capability, but economic problems slowed the momentum.
Still, South Korea manage to commission the Chungmugong Yi Sun-sin class destroyers, also
known as KDX II-class, in the early 2000s.
But, South Korea needed Aegis destroyers, and the Sejong Daewang-class was designed
to fulfil this requirement.
The first ship of the class, ROKS Sejong Daewang, was laid down on May 20, 2006, launched on
May 25, 2007, and commissioned on December 22, 2008.
The second and third destroyers, ROKS Yulgok Yi I and ROKS Seoae Ryu Seong-ryong, were
commissioned in 2010 and 2012, respectively.
These three vessels are defined as Batch I. On October 10, 2019, South Korea ordered three
additional Sejong Daewang-class destroyers as Batch II, which will be 4 metres longer
and 600 tons heavier than the previous ships.
The first vessel, ROKS Jeongjo Daewang, was laid down on October 5, 2021, and launched
on July 28, 2022.
She will be commissioned in 2024.
The Batch II Sejong Daewang-class destroyers will have two electric propulsion systems,
in addition to the existing four gas turbine engines, which provide fuel efficiency and
reduced noise.
The hull design of the Sejong Daewang-class is based on the U.S. Flight IIA Arleigh Burke-class
destroyer, but it is enlarged by about 10 per cent to accommodate more missiles.
The South Korean destroyer has 32 more vertical launching system cells than its Japanese and
U.S. Counterparts.
It even carries more missiles than the heavier Chinese Type 055-class destroyer.
So many experts define the Sejong Daewang-class as cruisers.
Indeed, it is bigger and more combat-capable than the U.S. Ticonderoga class.
Another difference between the hull design of the Sejong Daewang-class and Flight IIA
Arleigh Burke-class is their waterline shape.
Yet, the Korean news channel, YTN, claimed in 2014 that the noise level of the Sejong
Daewang-class exceeds the standard.
Some naval engineers assert that changing the waterline shape has caused this problem.
The complement of the Sejong Daewang-class is about 300-person.
The ship has a length of 165.9 metres, a beam of 21.4 metres, and a draught of 6.25 metres.
Its standard displacement is 7,650 tons, and its fully-loaded displacement is about 10,000
tons.
The combined gas and gas configuration propulsion system consists of four 25,000-horsepower
General Electric LM2500 gas turbines.
The top speed of the Sejong Daewang-class is 30 knots.
The range is nearly 10,200 kilometres, in other words, 5,500 nautical miles.
The Sejong Daewang-class has the Aegis Combat System Baseline 7 Phase 1, whose features
include AN/SPY-1D(V) radar upgrade, cooperative engagement capability and tactical ballistic
missile defence capability and advanced computer architecture.
So, one destroyer can direct the weapon systems of the other, which could not detect the threat,
to the target.
Thanks to its Aegis system, the Sejong Daewang-class can track and monitor missiles launched anywhere
in North Korea.
In 2009, the destroyer demonstrated this capability by tracking a North Korean missile.
Currently, the ROKN is considering installing Aegis Baseline 9 on the vessels.
If this plan is executed, the Sejong Daewang-class would have the capability of intercepting
hypersonic missiles.
The destroyer has 16 sea-skimming capable SSM-700K Haeseong anti-ship missiles with
a range of over 180 kilometres range and a speed of Mach 0.95.
The locally developed SSM-700K has a 250-kilogram warhead.
The Sejong Daewang-class has an 80-cell Mk 41 vertical launching system for the RIM-66
SM-2 Block IIIB and RIM-156A SM-2 Block IV air-defence missiles.
The Block IIIB SM-2, with over 160 kilometres range and Mach 3.5 maximum speed, is effective
against anti-ship missiles and other conventional air targets, such as aircraft and helicopters.
It adds an infrared guidance mode to Block IIIA to improve cruise missile intercepting
capabilities.
The Block IV variant, with anti-ballistic missile interception capability, can reach
a distance of 370 kilometres.
The ROKN is also considering acquiring the RIM-161 SM-3 and RIM-174 SM-6 for its Sejong
Daewang-class destroyers.
As mentioned before, the Batch I ships have the Aegis Baseline 7.
So, they can not perform "integrated air and missile defence" to supplement U.S. Army ground-based
THAAD missiles on the peninsula.
Therefore, even if they are also equipped with the SM-3, they cannot use these missiles
at full performance.
Thanks to their Aegis Baseline 9, the Barch II destroyers will have integrated air and
missile defence and SM-3 firing capability.
The Sejong Daewang-class has a 48-cell K-VLS vertical launching system for the Hong Sang
Eo anti-submarine warfare and the Hyunmoo III land attack cruise missiles.
The Hong Sang Eo, also known as K-ASROC Red Shark, is a torpedo-carrying missile with
19 kilometres range.
After reaching the threat zone, it leaves the passive/active sonar-homing K745 Cheong
Sang Eo torpedo.
The K745 Cheong Sang Eo has a range of 9 kilometres and a speed of 45 knots.
It is highly efficient in shallow waters.
Also, the Sejong Daewang-class can launch the K745 Cheong Sang Eos from its triple torpedo
tubes.
The INS/GPS/TERCOM guided Hyunmoo III land attack cruise missile has A, B, C and D variants
with 500, 1,000, 1,500 and 3,000 kilometres ranges, respectively.
It can carry a 500-kilogram warhead.
The missile has a speed of Mach 1.2.
The missiles of the RIM-116 RAM close-in weapon system have passive radar homing capability
and an infrared guidance system that enables it to intercept stealth targets.
Their effective range is over 9 kilometres, and their maximum speed is over Mach 2.
The 127mm 62 calibre Mk 45 Mod 4 naval gun has a stealthy turret design.
Its rate of fire is 40 rounds per minute.
The gun's maximum range is 37,000 metres.
The Goalkeeper close-in weapon system combines a 30mm seven-barrel gun, search and tracking
radars, an electro-optic tracker, and a laser rangefinder on one turret.
It can track 30 targets simultaneously, and the fire control computer can engage four
of them in order of priority.
The Goalkeeper has a rate of fire of 4,200 rounds per minute and a maximum effective
range of 3 kilometres.
The Sejong Daewang-class has aviation facilities that allow the operation of two Super Lynx
Mk.99s or MH-60Rs.
When we talk about the Sejong Daewang-class, many of our viewers naturally begin to compare
these destroyers with their Chinese counterparts.
Or they try to anticipate if can the Sejong Daewang-class deal with North Korea's swarm
naval or ground-based anti-ship missile attacks.
Currently, many assume the only power struggle in the East Pacific is between China/Russia/North
Korea axis and the U.S.-led allies.
But, it is not entirely true.
As mentioned before, the tension around the Dokdo islets between South Korea and Japan
paved the way for the emergence of the Sejong Daewang-class.
South Korea controls the Dokdo islets, but it causes a sovereignty dispute with Japan.
Therefore, these two countries have experienced some crises around the area.
So, when we talk about the Sejong Daewang-class, we should also compare it with the Japanese
Kongō, Atago and Maya class destroyers.
However, we must admit that these surface combatants of the ROKN have participated in
many RIMPAC exercises and trained for joint operations with the Japanese warships in alliance
spirit.
Also, South Korea immediately dispatched its Aegis destroyers to prepare for unforeseen
circumstances whenever North Korea conducted a ballistic missile trial.
So, even though the Sejong Daewang-class was initially designed against Japan - at least
according to official statements - it is now an essential part of the U.S.-led alliance
against the China/Russia/North Korea axis due to the disrupted power balance in the
region.
Besides, we should remember that South Korea has changed its defence policy since 2015.
So, one of the primary missions of the Republic of Korea Armed Forces is to prevent a possible
North Korean ballistic missile attack and, after that, to carry out a quick retaliatory
strike on North Korean officials as a part of its "Massive Punishment and Retaliation"
strategy.
The Sejong Daewang-class, which can track and monitor missiles launched anywhere in
North Korea, is a perfect platform for this job.
The Sejong Daewang-class destroyers carry more missiles than their Chinese and Japanese
counterparts.
They have the same combat systems and fire control radars as the Kongō, Atago and Maya
classes have.
But, the Japan Maritime Self-Defense Force's destroyers can launch the RIM-161 SM-3 missiles.
The Chinese ships have more stealthy designs.
Also, according to the South Korean media, the Sejong Daewang-class has a high noise
problem, while its Japanese and Chinese counterparts do not.
Still, its U.S.-made electronics and missiles are more capable than the Type 055's.
Another interesting fact about the Sejong Daewang-class is its size, displacement and
combat capability.
In general opinion, it is not a destroyer but a cruiser.
Also, the vessels of the previous KDX I and KDX II programmes are not destroyers but frigates
in terms of size, displacement and combat capability.
So, after the fruit of the three-stage destroyer-building programme, the ROKN does not even have a single
warship to be described as a destroyer by international standards.
The Sejong Daewang-class vessels may not able to change the balance in the region alone,
but they can undoubtedly disturb it.
It is an essential piece in the Asia Pacific chessboard.
These destroyers can save South Korea from the devastating effects of a possible North
Korean ballistic missile attack.
Indeed, the Sejong Daewang-class destroyers are among the most deterrent elements of the
ROKN.
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