South Korea’s Defense Acquisition Program Administration signed a formal construction contract with Hanwha Ocean on July 31 for the detailed design and lead ship of the Korea Destroyer Next Generation — the KDDX — a six-ship, ₩7.8 trillion (approximately $5.41 billion USD) program that will give the Republic of Korea Navy its first fully indigenous Aegis-class destroyer. The signing ends more than two years of industrial dispute, criminal proceedings, and competitive bidding that had kept the program in limbo — and it formally commits South Korea to a warship architecture built on technologies the country has been quietly developing for more than a decade.

What distinguishes KDDX from every destroyer South Korea has built before it is not the headline numbers. It is three specific technical decisions locked in with this contract: an Integrated Electric Propulsion System (IEPS), a domestically developed dual-band phased-array radar in a unified mast, and a Korean-made combat management system to tie them together. Together, they amount to a declaration that the Republic of Korea Navy intends, for the first time, to field a large surface combatant without relying on the American Aegis Combat System it has used since the 1990s.

The program represents one of the most significant shifts in South Korea’s naval self-sufficiency posture in decades — and the contract that just closed sets the clock running toward a 2032 delivery target that will test Hanwha Ocean’s ability to execute at pace.

Hanwha Won by Half a Point — Over a Rival That Did the Design Work

The procurement story is as consequential as the technology. Hanwha Ocean — formerly Daewoo Shipbuilding and Marine Engineering before the Hanwha Group acquired it in 2023 — defeated rival HD Hyundai Heavy Industries by just 0.5867 points in DAPA’s formal scoring. That margin is the width of a rounding error in a major national security procurement, and it did not emerge from a technical verdict alone.

HD Hyundai Heavy Industries had completed the KDDX basic design in December 2023 — the foundational engineering work that Hanwha Ocean must now convert into production drawings. In technical scoring, HD HHI led Hanwha Ocean: HD HHI received 73.2383 raw technical points against Hanwha’s 72.5958. The outcome turned on a 1.2-point security deduction applied to HD HHI over a military secrets scandal that resulted in eight employees receiving final guilty verdicts in 2022, with a ninth convicted in December 2023, all in cases involving unauthorized acquisition and dissemination of KDDX conceptual design data. HD Hyundai filed an injunction to block the selection; a South Korean court dismissed it on June 5, 2026.

Hanwha’s final score was 93.9542 against HD HHI’s 93.3675. The margin is historically small for a national fleet recapitalization. It also creates a practical engineering challenge: Hanwha Ocean must execute detailed design and construction on a basic design largely authored by a rival shipbuilder.

What “Indigenous Aegis-Equivalent” Actually Means

South Korea’s existing top-tier destroyers — the KDX-III Sejong the Great-class and the newer Jeongjo the Great-class — are genuine Aegis ships. They use the American AN/SPY-1D radar and the Aegis Combat System, which is controlled by the US Navy and subject to export restrictions, operational limitations, and interoperability constraints that Seoul has no power to change. The KDDX abandons that dependency by design.

The central technical elements of the KDDX are:

Dual-Band Phased-Array Multi-Function Radar in an Integrated Mast: KDDX carries a domestic S/X dual-band Active Electronically Scanned Array housed in an Integrated Mast (I-MAST) — a single enclosed superstructure rather than separately mounted antennas. S-band (2-4 GHz) provides long-range volumetric search; X-band (8-12 GHz) provides the shorter-wavelength precision needed for fire-control guidance. Combining both in one mast reduces topside weight and radar cross-section compared to separate installations, and eliminates the signal handoff latency that exists when an S-band search radar passes a track to a separate X-band fire-control system. The US Aegis uses only S-band.

Integrated Electric Propulsion System (IEPS): KDDX will be the first Korean warship to use IEPS — a fully electric drive architecture in which gas turbines and diesel generators operate only as generators, feeding power to an electric bus that drives both the propulsion motors and every other system aboard the ship. The contrast with conventional propulsion matters: in a standard CODAG or COGAG arrangement, the engine shaft connects mechanically to the propeller, and the vibration from that transmission propagates through the hull into the water as Underwater Radiated Noise (URN) — acoustic energy that submarines can detect. Severing that mechanical connection eliminates a major noise source. IEPS provides measurably quieter acoustic signatures, directly improving the ship’s survivability against hostile submarines and its effectiveness in anti-submarine warfare.

The noise reduction is the operational benefit today. The strategic benefit is electrical margin. The Zumwalt-class destroyer, the US Navy’s IEPS platform, generates approximately 78 megawatts of electricity — enough to power future directed-energy weapons at scale. South Korea’s KDDX is designed with that same growth principle in mind: whatever high-power sensors, electronic warfare systems, or laser-based close-in weapons arrive in the 2040s, the electrical bus will be there to run them. Hanwha Ocean and GE Aerospace co-developed the KDDX propulsion system, building on research DSME (Hanwha’s predecessor) completed in 2019-2020.

Indigenous Combat Management System and KVLS-II: The ship’s combat management system is Korean-made — another first for a large Korean surface combatant. Armament includes domestically produced missiles via Korean Vertical Launch System cells of two variants: KVLS-I handles existing rounds including the Hyunmoo-3C land-attack cruise missile and SSM-700K anti-ship missiles; KVLS-II provides the larger cell needed for Ship-to-Air Missile-II, a long-range naval air defense weapon under development by LIG Nex1 with approximately 90% domestic content.

Why the Navy Needs This Class Specifically

South Korea already fields some of the most capable destroyers in Asia. The KDX-III Sejong the Great-class are large Aegis ships purpose-built for ballistic missile defense — and they are few, expensive, and already fully committed to that mission. The KDX-I Gwanggaeto the Great-class, the oldest destroyers in service, are aging out and need replacement. Between those two tiers sits a gap: no modern Korean destroyer of intermediate size capable of fleet escort, maritime patrol, strike missions, and submarine hunting without overcommitting the high-end Aegis assets.

KDDX fills that gap with six hulls — each displacing approximately 7,100 metric tons (7,826 short tons) at light load, measuring 155 meters (508 feet) long, 18.8 meters (61.7 feet) in the beam, and drawing 9.5 meters (31.2 feet). The design also incorporates automation to reduce crew requirements compared to older destroyer classes, a direct response to a documented ROK Navy recruitment shortfall.

What Hanwha Ocean Is Building Into the Design

The contract phase brings three technologies not in the original basic design, all incorporated into the detailed design now beginning:

A digital twin framework creates a living computational replica of the ship, used to simulate construction sequences, test equipment fit-check, and validate combat system integration before physical work begins. This reduces rework — the kind of expensive late-discovery problem that has dogged American shipbuilding programs, including the Constellation-class frigate, which began construction before completing its design.

A multi-layered counter-UAS architecture integrates dedicated drone defense systems from the outset rather than retrofitting them later. Hanwha specifically cited the proliferation of drone threats in Ukraine and the Middle East as the driving rationale — conflicts that demonstrated the vulnerability of surface vessels to small, cheap unmanned systems.

An embedded 5G network provides high-bandwidth wired and wireless connectivity throughout the ship, enabling the network-centric warfare architecture the ROK Navy expects to operate in by the time KDDX commissions.

Hanwha Ocean also plans to integrate a manned-unmanned teaming capability and a cyber defense framework, with nine total domestically developed systems aboard the ship.

Schedule, Money, and What Comes Next

The ₩838 billion (approximately $581 million USD) lead ship contract runs through June 30, 2032 — the KDDX’s delivery deadline. Procurement of the five follow-on ships is expected to begin in late 2028, with the full fleet scheduled for delivery by 2036.

The total program, including development and construction of all six hulls, is valued at ₩7.8 trillion (approximately $5.41 billion USD), comprising roughly ₩1.8 trillion (approximately $1.25 billion USD) in development costs and ₩6 trillion (approximately $4.16 billion USD) in construction costs.

The schedule is tight. The basic design was completed in December 2023, with detailed design originally expected to follow immediately; the two-year industrial dispute and legal fight cost the program that margin. Hanwha and DAPA will need to compress portions of the design and construction sequence to meet the 2032 target.

In similar Korean programs, the contractor awarded the lead ship has historically gone on to secure follow-on orders, which would make the ₩838 billion lead ship contract a down payment on a substantially larger long-term relationship for Hanwha Ocean.

Seoul’s Bigger Ambition

DAPA’s head of advanced capabilities, Jung Jae-jun, did not describe the KDDX as a domestic defense program at the signing ceremony. He described it as a platform to strengthen “the global competitiveness of K-warships in export markets”. That framing is consistent with South Korea’s broader defense export trajectory: the country’s arms sales topped $17 billion in 2022, more than double the prior record, and Seoul has set a goal to become the world’s fourth-largest weapons exporter by 2027.

A KDDX that delivers on its technical promises — indigenous Aegis-equivalent radar, electric propulsion, domestic combat management — would be a credible export platform for middle-power navies in Asia, the Middle East, and beyond, in the same tier as the KSS-III submarine that Hanwha is already pitching to Canada and other export customers.

Kim Ho-jung, Hanwha Ocean’s executive director for domestic sales, said the company “feels a heavy responsibility as the contractor for the KDDX detailed design and lead ship construction.” That responsibility includes delivering a ship that works well enough to become South Korea’s next defense export franchise.

The clock started July 31.

Currency conversions in this article are approximate, based on exchange rates at time of publication and subject to change.

Frequently Asked QuestionsWhat is the KDDX, and how is it different from South Korea’s existing Aegis destroyers?

KDDX is a new class of six destroyers being built by Hanwha Ocean for the Republic of Korea Navy, with the first ship due in 2032. Unlike South Korea’s existing KDX-III Sejong the Great-class ships — which use the American AN/SPY-1D radar and US Aegis Combat System — the KDDX is designed entirely around domestically developed technology: its own dual-band phased-array radar, its own combat management system, and its own vertical launch missiles. It is the first large Korean surface combatant not dependent on the American Aegis architecture.

Why did Hanwha Ocean win instead of HD Hyundai Heavy Industries, which did the design work?

HD HHI actually led in the raw technical evaluation by about 0.65 points. The outcome was reversed by a mandatory 1.2-point security penalty applied to HD HHI because employees were convicted of stealing KDDX design data from Hanwha’s predecessor company. After the penalty, Hanwha won by 0.5867 points — a margin that remains unusually narrow for a national fleet program. HD HHI’s court challenge was dismissed in June 2026.

What does “Integrated Electric Propulsion” mean on a warship, and why does it matter?

Instead of connecting engines mechanically to propeller shafts — which transmits vibration through the hull as detectable underwater noise — IEPS runs gas turbines and diesel generators purely as electricity producers. Electric motors drive the propellers, and the same electrical bus powers every other system. The acoustic benefit: eliminating mechanical shaft vibration significantly reduces the ship’s noise signature, making it harder for hostile submarines to detect and easier for the ship to run its own sensors in a quiet environment. The strategic benefit: the electrical bus provides substantial growth margin for future high-power systems, including potential directed-energy weapons, during KDDX’s expected operational life into the 2060s.

Is the KDDX actually an Aegis destroyer?

Not in the American sense. It does not use the US Aegis Combat System or the AN/SPY radar family. It is often called a “mini-Aegis” or “Korean Aegis” because it performs similar air defense and multi-mission functions — with its own dual-band AESA radar providing volume search and fire control, and its own combat management system coordinating weapons and sensors — but the underlying technology stack is entirely Korean. Whether it delivers equivalent radar performance to the Aegis system is something DAPA and the ROK Navy will learn during testing and evaluation before 2032.