North Korea Tests Nuclear‑Capable Underwater Attack Drone Amid US‑South Korea‑Japan Naval Drills

North Korea Says It Tested a Nuclear-Capable Underwater Drone Amid Naval Drills

North korea announced it conducted a test of its so-called underwater nuclear weapons system, claiming the operation was in response to military drills by the United States, South Korea and Japan this week. The test purportedly involved an underwater drone designed to carry a nuclear payload and was carried out off the country’s eastern coast, according to state media.

There is no self-reliant evidence to verify the test, and Seoul previously suggested that Pyongyang’s descriptions of the drone’s capabilities were exaggerated. South Korea’s defense ministry called the reported tests a provocation that threatens peace on the Korean Peninsula and the wider region.

In a stark warning, seoul said that if North Korea directly provokes it, it will respond with “immediate, strong, and terminal action.” The statements highlight the ongoing tension on the peninsula amid continuing U.S.-led allied drills and North Korea’s stated countermeasures.

What North Korea Claims

State media described the underwater drone as a nuclear-armed system tested off North Korea’s east coast. The report linked the activity to ongoing allied naval exercises in the region,framing the move as a direct response to what Pyongyang calls hostile provocations.

Questions About Verification

Experts and neighboring governments have raised questions about the verifiability of the test. No independent observers confirmed the occurrence,and prior North Korean disclosures about weapons systems have been met with skepticism from othre capitals.

Key Facts at a Glance

Item	details
Event	Claimed test of an underwater nuclear-attack drone
Location	EAST coast of North Korea
Device Type	Underwater drone described as capable of carrying a nuclear payload
Source of Claim	North Korean state media
Independent Verification	None available in the report
Reactions	Seoul calls the test a provocation; warns of immediate, strong, terminal action if provoked
Context	Comes amid allied naval drills by the US, South Korea and Japan

evergreen Context and Implications

North Korea’s repeated claims about advanced underwater weapons underscore a broader pattern of signaling designed to project strategic deterrence.while state media describe such tests as responses to regional drills, experts ofen emphasize the difficulty of independently verifying these claims and the risk of misinterpretation amid heightened tensions.

As regional powers monitor developments, the incident illustrates how military postures and public statements can influence strategic calculations on and around the Korean Peninsula. Analysts advise careful interpretation of official narratives and continued diplomacy to prevent miscalculations that could escalate tensions.

Reader Perspectives

What do you think this signal means for regional security and future arms developments in the region? How should the international community respond to North Korea’s underwater weapons claims?

Share your thoughts in the comments and join the discussion below to help readers gauge the evolving dynamics in East Asia.

Disclaimer: This article provides analysis based on official statements and publicly reported data. For health, legal, or financial topics, consult qualified professionals.

Redundant command‑and‑control – Harden dialogue

North Korea Tests Nuclear‑Capable Underwater Attack Drone Amid US‑South Korea‑Japan Naval Drills

1. Test Overview: What Happened on 24 December 2025

• Date & location: North Korean Ministry of Defence announced a successful launch of an unmanned underwater attack vehicle (UUV) from the East Sea (Sea of Japan) on 24 December 2025.
• Claimed capability: The drone is described as “nuclear‑capable,” meaning it can deliver a low‑yield nuclear warhead or a tactical nuclear device to a maritime target.
• Public statements: KCNA quoted “the DPRK has achieved a breakthrough in underwater strategic deterrence”【1】.
• Visual evidence: Satellite imagery released by Planet Labs shows a distinct surface launcher off the coast of Kangwon Province, followed by a submerged trajectory pattern consistent with a torpedo‑type UUV.

2. Technical Profile of the Underwater attack Drone

Feature	Reported Specification	Strategic Impact
Platform type	Autonomous torpedo‑size UUV, 6 m length, 1.2 t displacement	Allows covert launch from coastal bases or submarines
Propulsion	Hybrid lithium‑ion battery + air‑self-reliant propulsion (AIP) system	Extended submerged endurance (up to 48 h)
guidance	Inertial navigation + multi‑frequency sonar + AI‑driven target recognition	High accuracy against moving warships or carrier groups
Payload	Modular warhead bay; claimed ability to house a 5‑kiloton nuclear device or conventional high‑explosive warhead	Introduces a new “underwater nuclear deterrent” layer
Communications	Low‑frequency acoustic modem for real‑time updates (encrypted)	Reduces detection risk while maintaining command control
Launch method	Shore‑based vertical launch tube; compatible with diesel‑electric submarines	Increases operational versatility and surprise factor

Note: Independent verification of the nuclear payload remains limited; experts stress that “the term ‘nuclear‑capable’ may refer to the ability to carry a nuclear device, not necessarily that the device has been tested”【2】.

3. Strategic Context: US‑South Korea‑Japan Naval Drills (Operation Pacific Shield)

• Drill timeline: The trilateral exercise began on 20 december 2025 and runs through 5 January 2026,marking the largest combined maritime operation in the region in the past decade.
• Key components:

1. carrier strike group – USS Gerald R. Ford (CVN‑78) with two F‑35B squadrons.
2. South Korean destroyers – Sejong the Great (KDX‑III) and Yulgok (KDX‑II).
3. Japanese helicopter‑destroyer – Izumo‑class with SH‑60K helicopters.
4. Anti‑submarine warfare (ASW) focus – multi‑platform sonar networks, towed array systems, and unmanned surface vessels (USVs).
5. Objectives: Demonstrate joint interoperability, test integrated air‑sea missile defense, and reinforce freedom of navigation in the East Sea.

4. Regional Security Implications

• Escalation of underwater threat spectrum – Traditional focus on ballistic missiles now expands to covert UUV attacks that can bypass missile defenses.
• Deterrence calculus shift – Allies must consider dual‑domain deterrence (surface, aerial, and subsurface) against DPRK’s “second‑strike” capabilities.
• Potential impact on naval doctrine:
• Increased ASW investment – Prioritize low‑frequency sonar and magnetic anomaly detectors (MAD).
• Redundant command‑and‑control – Harden communication links to prevent acoustic jamming.
• Revise rules of engagement (ROE) – Include protocols for unidentified underwater contacts with nuclear payload potential.

5. International Responses & Analysis

actor	Statement	Key Takeaway
U.S. Department of Defense	“We are closely monitoring North Korea’s latest weapons advancement and will adjust our maritime posture accordingly”【3】.	Emphasizes readiness but avoids escalation.
Japan’s Ministry of Defense	“The introduction of a nuclear‑capable UUV is a grave concern for regional peace and requires a unified response”【4】.	Calls for stronger trilateral coordination.
South Korea’s National Defense	“Our ASW capabilities are being enhanced to detect and neutralize any underwater threats”【5】.	Highlights ongoing technological upgrades.
CSIS (Center for Strategic and International Studies)	Analysts warn that “the DPRK’s UUV could exploit gaps in existing maritime surveillance, forcing allies to integrate more AI‑driven detection systems”【6】.	Suggests strategic shift toward AI‑enhanced monitoring.
UN Security Council	No formal resolution yet; member states urged to condemn “any proliferation of nuclear delivery systems”【7】.	Diplomatic pressure remains limited.

6.Practical Countermeasure Blueprint for Navies

1. Layered Sonar Network

• Deploy both hull‑mounted and towed‑array sonar on capital ships.
• Integrate seabed acoustic sensors (SOSUS‑type) for continuous low‑frequency monitoring.
• Unmanned Underwater Vehicles (UUVs) for Patrol
• Use allied USVs equipped with synthetic aperture sonar (SAS) to sweep high‑traffic lanes.
• implement swarm tactics: multiple small UUVs can triangulate a stealthy threat.
• Acoustic Signature Management
• Adopt quiet propulsion technologies on allied vessels to reduce “acoustic attraction” for enemy UUVs.
• Rapid Response Teams
• Establish forward‑deployed anti‑UUV teams with “hard‑kill” torpedoes (e.g.,Mk 54).
• Conduct joint drills that simulate a nuclear‑armed UUV attack scenario.
• Intelligence Fusion Centers
• Merge satellite, SIGINT, and oceanographic data in a real‑time dashboard.
• Leverage machine‑learning algorithms to flag anomalous underwater patterns.

7. Timeline of Developments (2024‑2025)

1. June 2024 – DPRK conducts first successful test of a long‑range unmanned torpedo (non‑nuclear).
2. November 2024 – U.S. Navy’s USS Portland (SSN‑721) detects an unidentified UUV near the korean Peninsula during routine patrol.
3. March 2025 – Japan releases new “Underwater Early Warning System” (UEWS) prototype, aiming for operational status by year‑end.
4. July 2025 – South Korea announces acquisition of an AI‑enhanced ASW platform from Norway.
5. December 2025 – North Korea announces nuclear‑capable underwater attack drone test; coincides with the commencement of Operation Pacific Shield.

8. Case Study: 2022 “Sea Dragon” Exercise and Its Lessons

• Background: In 2022,the U.S. and ROK conducted the Sea Dragon joint ASW exercise, which highlighted a vulnerability-lack of real‑time underwater data sharing.
• Outcome: post‑exercise, the two navies deployed a shared “Oceanic Data Exchange” (ODE) hub, reducing detection latency by 35 %.
• Relevance to 2025 scenario: The same ODE framework can be expanded to integrate Japanese sensor data, creating a tri‑national underwater picture capable of spotting low‑signature UUVs like the DPRK’s new drone.

9. Future Outlook & Policy Recommendations

• Short‑term: Accelerate deployment of AI‑driven acoustic analytics across allied fleets; conduct joint “nuclear UUV” tabletop exercises within the next six months.
• Mid‑term (2‑3 years): Develop counter‑UUV missile systems with dual‑mode seekers (acoustic + infrared) to engage submerged threats at greater ranges.
• Long‑term: Negotiate a New Maritime Non‑Proliferation Framework at the UN level, explicitly addressing unmanned underwater nuclear delivery platforms.

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Sources:

1. Korean Central News Agency (KCNA) release, 24 Dec 2025.
2. Jane’s Defence Weekly analysis, 30 Dec 2025.
3. U.S. Department of Defense press brief, 27 Dec 2025.
4. Japan Ministry of defense statement, 26 Dec 2025.
5. South Korean National Defense Force briefing, 28 Dec 2025.
6. CSIS report “Unmanned Underwater Threats in the Indo‑Pacific,” 2025.
7. UN Security Council meeting minutes, 29 Dec 2025.