South Korea Green-Lights Its First Nuclear-Powered Submarines — But the Fuel Deal Is Still Missing

South Korea has given the formal go-ahead to build its first nuclear-powered submarines, a project that would put it in a small club of countries able to keep a submarine underwater almost indefinitely. But the programme still has a major gap: Seoul has not yet secured the nuclear fuel to power the boats.

The Defence Acquisition Program Administration (DAPA) approved the basic acquisition strategy for the Jang Bogo N programme on Friday, 6 November 2026. The decision clears the way for formal development to begin in 2027, with the first submarine targeted for launch in the mid-2030s and operational deployment in the late 2030s or beyond.

The submarines will be nuclear-propelled but carry conventional weapons — the reactor is the engine, not the warhead.

What was approved

The decision came at the 179th meeting of the Defense Acquisition Program Promotion Committee, held at the Ministry of National Defense on 6 November. The committee endorsed the basic plan for Jang Bogo N, also known as KSS-III Batch-III.

The programme aims to develop and build nuclear-powered attack submarines using South Korea’s own technology and industrial capacity. It was first unveiled in May 2026, and the November decision moves it from a political promise to a formal procurement programme.

DAPA said the submarines are expected to strengthen South Korea’s deterrence against North Korea’s nuclear and missile threats, and to expand the underwater capabilities of the country’s “Kill Chain” system — the part of South Korea’s defence designed to detect preparations for an attack and strike threatening targets before weapons are launched.

The same committee meeting also approved a series of other defence programmes, including a longer-range missile to counter North Korean artillery, better military radios, new harbour patrol boats, an unmanned mine-clearance vessel and replacement presidential helicopters.

Why nuclear power changes everything underwater

To understand why this decision matters, it helps to know the difference between the submarines South Korea has now and the ones it wants to build.

South Korea’s current submarines, including the Dosan Ahn Chang-ho class, run on diesel-electric power. They are quiet and capable, but they must manage stored electrical power carefully and come near the surface regularly to recharge their batteries. That limits how long they can stay hidden underwater and how far they can travel without being detected.

A nuclear-powered submarine does not have that problem. Its reactor keeps producing energy without needing air from the surface, so it can stay submerged for months at a time and travel much greater distances. That makes it far better at long surveillance missions, tracking other submarines across wide areas of ocean, and staying on station while waiting for a target.

That is exactly what South Korea says it needs. North Korea has been building submarines capable of launching ballistic missiles, and tracking them requires a boat that can stay underwater, move fast and cover large areas of sea.

A DAPA official underlined the scale of the step by comparing the new boat with the one South Korea already builds at home. The Dosan Ahn Chang-ho took about four years to design and five years to build. The official said a submarine powered by a reactor would take somewhat longer — and the proposed 8,000-ton vessel would be roughly 2.7 times the tonnage of the 3,000-ton Dosan Ahn Chang-ho.

The numbers: three boats, 8,000 tons, $21.3 billion

The plan under discussion is for at least three submarines, each of around 8,000 tons. Planning and Budget Minister Park Hong-keun estimated the programme at 28.9 trillion won, about $21.3 billion, in May. DAPA says the total budget is still being discussed and has not been finalised.

That makes Jang Bogo N one of the biggest defence commitments South Korea has ever made — a project that will run well beyond the current government. The first boat is not expected to enter the water until the mid-2030s, and it will need years of testing after that before it joins the Navy.

The schedule, as set out by DAPA, is:

• 2027: Formal development begins. A shipbuilder is chosen through open bidding in the first half of the year, and a construction contract is targeted by the end of the year.
• Mid-2030s: The first submarine is launched — meaning it enters the water for the first time.
• Late 2030s or beyond: The boat enters operational service, after testing, evaluation and acceptance by the Navy.

The South Korean newspaper Chosun Ilbo reported that the initial budget for the design phase is 96.6 billion won, and that design work alone is expected to take three to four years, followed by more than five years of construction.

Hanwha Ocean and HD Hyundai Heavy Industries are expected to compete for the hull design and construction work. Both companies have built submarines for the South Korean Navy before, and DAPA says domestic shipbuilders have the design and construction capability to support a competitive tender.

The fuel problem: Washington said yes, but the deal is not done

Here is the catch. A nuclear submarine needs nuclear fuel, and South Korea does not yet have a settled arrangement to get it.

Washington has given political consent to South Korea’s pursuit of submarines powered by reactors using uranium enriched to below 20 percent — a type of fuel known as high-assay, low-enriched uranium, or HALEU. The joint fact sheet that followed President Lee Jae Myung’s summit with President Donald Trump in October 2025 committed the United States to working with South Korea on the project, including arrangements to obtain fuel.

But the practical arrangements remain unfinished. Bilateral security talks opened in Seoul in June 2026, covering submarine construction, uranium enrichment and the reprocessing of spent nuclear fuel. A second round planned for Washington in July has not taken place, and no date has been given for it.

The Korea Times reported on 8 November that Seoul has not secured the nuclear fuel and cooperation it needs from the United States, and is pursuing a separate military nuclear cooperation arrangement under Section 91 of the US Atomic Energy Act, rather than revising the existing nuclear cooperation agreement, which covers civilian uses.

A DAPA official has said that starting the project before the fuel negotiations conclude would require a policy and political judgment. For Seoul, the immediate challenge is coordinating a domestic timetable — bidding in 2027, a contract by the end of that year — with an international fuel agreement that is still open.

There is a precedent for this kind of arrangement. Australia’s AUKUS deal, under which Australia will acquire nuclear-powered submarines with American and British help, required a similar set of agreements on fuel and technology. A separate agreement comparable in approach to Australia’s AUKUS arrangements is one of the options under consideration for South Korea.

Built at home, not in America

One question that has already been settled is where the submarines will be built: in South Korea.

That had become a public issue after President Trump named Philadelphia — where Hanwha owns a shipyard — when announcing US approval in 2025. But South Korean officials have been clear that the hull and reactor will be manufactured at home, while the enriched uranium fuel would come from the United States.

Wi Sung-lac, director of the National Security Office, put it plainly during a National Assembly appearance: “Right now, we are not considering building them in the United States. We are considering building them ourselves.”

The presidential office has also said the submarine should be tailored to South Korea’s operational needs and differ from the US Virginia-class design. That points to a domestic development effort rather than simply buying an existing American submarine.

Under the plan, the government will procure the small modular reactors (SMRs) that power the boats directly, along with certain missile systems, and supply them to the winning shipbuilder. The shipbuilder will act as the system integrator, bringing the hull, propulsion equipment, weapons and other systems together into a working submarine.

The fast track: why the usual checks were skipped

Jang Bogo N is moving unusually fast for a project of this size. In August 2026, the Ministry of Planning and Budget granted the programme an exemption from the preliminary feasibility study that major defence purchases normally require.

Such studies usually take one to two years and examine whether a big acquisition should go ahead before the government commits to development. Procurement rules allow the defence minister or the DAPA chief to request an exemption for highly classified projects, and the ministry used a national security exception because of the secrecy the submarine programme requires. A separate detailed assessment is still planned.

The Navy has already begun preparing. At a parliamentary audit on 20 October, it described a temporary submarine task force established on 1 May, with 17 personnel across three teams, covering construction, testing, deployment and the units needed to operate the vessels.

But the speed has also drawn questions. At the same audit, lawmakers asked whether the government had defined the submarines’ missions clearly enough, and whether other vessels could perform those missions at a lower cost.

The wider build-up approved on the same day

Jang Bogo N was the biggest item on the committee’s agenda, but not the only one. The same meeting approved:

• A longer-range artillery missile. The second block of the Korean Tactical Surface-to-Surface Missile-I (KTSSM-I), known as the “artillery killer”, is designed to destroy North Korean long-range artillery threatening the Seoul metropolitan area. The upgraded version is expected to have a range about 30 percent greater than the original. The programme runs from 2028 to 2035 at an estimated cost of 537 billion won, about $395 million.
• Better military communications. A revised plan for mass production of the Tactical Multiband Multirole Radio (TMMR) system.
• New harbour patrol boats and mine clearance. Replacement harbour patrol boats and an upgrade to an unmanned surface vessel designed for mine clearance.
• New presidential helicopters. Sikorsky’s S-92A Plus was selected to replace the ageing presidential helicopter fleet, with new aircraft due from 2031. The programme is valued at 873 billion won.

Together, the decisions show a broader push to strengthen South Korea’s military across the board — at sea, in the air and in communications — as tensions with North Korea persist.

Why it matters for the region

Today only a handful of countries — the United States, Russia, China, Britain, France and India — operate nuclear-powered submarines. South Korea would join that group, and it would be the first country to do so with American consent but without buying an existing foreign design.

That has implications beyond the Korean Peninsula. China watches any growth in allied naval power in the region closely, and North Korea will see the programme as a direct response to its own submarine-launched missile development. The boats are still more than a decade from service, but the decision itself sends a signal now: South Korea intends to be able to find and follow North Korean missile submarines wherever they go.

It also matters for the United States. Washington’s consent to the programme was a major political decision, and the unresolved fuel question shows how hard the practical side is. The same issue — who supplies the fuel, under what legal agreement — was one of the hardest parts of the AUKUS deal, under which Australia is acquiring nuclear-powered submarines with American and British help. How the United States and South Korea solve it will shape not only this programme, but how other American allies think about similar requests in future.

What happens next

The programme’s next steps are clear, even if the fuel question is not.

In the first half of 2027, DAPA plans to prepare its basic system development plan and open bidding for the shipbuilder. A construction contract is targeted by the end of 2027. At the same time, Seoul will need to close the fuel arrangement with Washington — the second round of talks, postponed since July, has no date yet.

After that comes the work: three to four years of design, more than five years of construction, then testing before the first boat can join the Navy in the late 2030s.

The fuel talks are the part to watch most closely. A submarine without fuel is a very expensive steel tube. If Washington and Seoul reach an agreement soon, the 2027 timetable can hold. If the talks drag on, the whole programme could slip — and South Korea’s entry into the nuclear submarine club would be delayed with it.

Frequently asked questions

What is Jang Bogo N?

It is South Korea’s programme to build nuclear-powered attack submarines, also known as KSS-III Batch-III. The boats will be nuclear-propelled but carry conventional weapons.

When was it approved?

South Korea’s Defence Acquisition Program Administration approved the basic acquisition strategy on 6 November 2026, at its 179th committee meeting.

How many submarines will South Korea build?

Media reports suggest at least three, each of around 8,000 tons. The total budget has not been finalised, but the planning and budget minister estimated it at 28.9 trillion won, about $21.3 billion, in May 2026.

When will the first one be ready?

The first submarine is targeted for launch in the mid-2030s, with operational deployment in the late 2030s or beyond.

What is the fuel problem?

The United States has agreed in principle to South Korea using uranium enriched to below 20 percent, but the practical deal to supply that fuel has not been agreed. Talks opened in June 2026, and a second round planned for July has not happened.

Why does South Korea want nuclear submarines?

To strengthen deterrence against North Korea’s nuclear and missile threats, including tracking North Korean submarines that can launch ballistic missiles. Nuclear power lets a submarine stay underwater far longer than a diesel-electric boat.

Where will they be built?

In South Korea. The government will buy the small modular reactors directly and supply them to the winning shipbuilder, with Hanwha Ocean and HD Hyundai Heavy Industries expected to compete for the contract.

Are these nuclear-armed submarines?

No. The submarines are nuclear-powered, meaning a reactor provides the energy to move them. They will carry conventional weapons, not nuclear ones.

Conclusion

The approval of Jang Bogo N is the biggest step South Korea has taken towards a nuclear-powered navy — and one of the most consequential defence decisions in the region this year. It commits the country to more than a decade of work, tens of billions of dollars, and a submarine it has never built before.

But the decision also leaves the hardest question open. Until Seoul and Washington agree on the fuel, the programme is a plan without its most important ingredient. The bidding in 2027 will show whether South Korean shipyards are ready. The fuel talks will show whether the politics are.

For now, South Korea has chosen its direction: underwater, for longer, and further from home than ever before.

Sources

• Yonhap News, via The South Asia Times, “South Korea approves plan for nuclear-powered submarine programme”, 6 November 2026: https://www.thesouthasiatimes.com/story/SouthKorea-Nuclear-Nov6
• Asia Daily, “South Korea Approves Nuclear Submarine Plan for 2027”, 6 November 2026: https://asiadaily.org/news/17871/
• Army Recognition, “South Korea Fast-Tracks New Nuclear Submarine Project to Hunt North Korean Ballistic Missile Subs”, 7 November 2026: https://www.armyrecognition.com/news/navy-news/2026/south-korea-fast-tracks-new-nuclear-submarine-project-to-hunt-north-korean-ballistic-missile-subs
• Global Military, “South Korea Approves Acquisition Strategy for Jangbogo N Nuclear-Powered Submarine”, 9 November 2026: https://www.globalmilitary.net/news/south-korea-approves-jangbogo-n-nuclear-powered-submarine-program/
• FN News, “South Korea Sets Sail on Indigenous Development of a ‘Nuclear-Powered Submarine'”, 6 November 2026: https://en.fnnews.com/news/202611061351596977
• Yonhap News, “Arms review committee approves plan for nuclear-powered submarine project”, 6 November 2026: https://en.yna.co.kr/view/AEN20261106007751315

This article is for general information and education only. It is not legal or financial advice.