North Korea's First Nuclear-Powered Submarine: A Game-Changer in Naval Power

North Korea has made headlines with the reveal of its very first nuclear-powered submarine. This massive underwater vessel, weighing 8,700 tons, marks a significant step up for their military. It's designed to carry missiles and stay hidden deep in the ocean for long periods. Kim Jong Un himself checked it out, calling it a key part of defending against threats from neighbors like South Korea and the US. Built in secret at an indoor shipyard, this sub shows North Korea's push to modernize its navy. But questions remain about how ready it really is, given the tech challenges involved.

This huge sub can stay underwater for months without needing to surface for fuel, unlike its older diesel subs. But details on the reactor are still mostly secret – no official specs on power output or exact type have been released. Here's what we know from recent reports and expert analysis as of late 2025.

Let's check out some real hidden facts about the first-ever nuclear power submarine

Likely Already Installed Reactor

Experts say the hull photos from December 25, 2025, show it's built "inside out," meaning the nuclear reactor and key propulsion parts (like turbines and cooling systems) are probably already inside the completed hull.

Unlimited Underwater Endurance

Nuclear propulsion gives it near-endless range and time submerged, only limited by food and crew needs – a huge upgrade for stealthy patrols and missile launches.

No Diesel Snorkel Needed

Photos show modern masts for optics and comms, but no classic snorkel mast for diesel engines, which points strongly to true nuclear power rather than a diesel-electric hybrid.

North Korea Discloses Ongoing Construction of an 8,700-Ton Nuclear

Highly Enriched Uranium Fuel

Analysts believe it uses uranium enriched over 90%, allowing the reactor to run the sub's whole life without refueling – simpler but riskier due to proliferation concerns.

Possible Russian Assistance

Many experts think Russia helped with tech or even parts from old subs, in exchange for North Korea's support in Ukraine – though some say it's mostly home-designed with limited outside help.

Compact Naval Reactor Design

It's a small, submarine-specific reactor, not like their bigger land-based ones – a tough tech hurdle that North Korea claims to have cracked since announcing the project in 2021.

Sea Trials Soon Possible

With the hull nearly done and reactor likely fitted, some analysts predict it could hit the water for tests in months, powering up the propulsion system for real.

Stealth and Acoustic Focus

The design includes advanced sonar and quieting features, helped by nuclear power's steady, low-noise operation compared to diesel subs.

Part of Strategic Deterrence

The propulsion lets it carry nuclear missiles farther and hide better, making North Korea's sea-based nukes harder to track and destroy in a conflict.

Unconfirmed Maturity

While progress looks real, no independent proof of a working reactor exists yet – it could face delays if testing reveals issues, like many new sub programs do.

This development ramps up tensions in Asia, but it's a reminder of how naval tech is evolving fast. If you're tracking military news or submarine tech, this is one to watch.