We tracked a North Korean dark ship
Here's how it stays in the shadows
It’s the middle of the night in April 2023 in the East China Sea.
A North Korean-linked oil tanker, sailing under different country's flag, suddenly goes dark.
It stops transmitting its location using the Automatic Identification System (AIS) machine that all larger commercial ships have on board. To the casual observer looking at a computer screen, it ceases to exist.
Ten days later, the ship reappears on the screen. Its AIS signal shows it is off the coast of southern China.
But the ship itself had never left its original location. We know because we spotted it by satellite.
It's called New Konk and it was preparing for a voyage to deliver sanctioned oil.
This is just one of hundreds of ships in the North Korean shadow fleet that keeps the pariah state's economy afloat in the face of international sanctions.
North Korea isn’t the only country with a shadow fleet. Russia has also amassed hundreds of dark ships to evade sanctions following its invasion of Ukraine in 2022. And Iran is using its shadow fleet to dodge the US blockade on its ports.
But North Korea is the pioneer of this murky world.
The hermit state launched its dark fleet more than a decade ago in response to UN sanctions over its nuclear weapons and missile programs. Now, its fleet is believed to include up to 750 vessels, though the exact figure will never be known.
One of us (Justin) has been tracking North Korea’s sanction evasion efforts, including its shadow fleets, for more than a decade. In a partnership between the University of Sydney and the National University of Singapore’s Centre of Maritime Studies, the three of us have also tracked the methods these ships use to obscure their identities and create new methods to try to detect them at sea.
This is the story of one ship in North Korea's fleet, the New Konk.
A shadow ship is born
Before New Konk became, well, New Konk, it was just an ordinary cargo vessel. It was built in 1991 in Japan and operated by South Korean firms, doing unremarkable shipping runs around the world.
An image taken in 2012 when the ship was legally registered under a different name, the Woo Bong. Image: Nesterka, Marine Traffic
An image taken in 2012 when the ship was legally registered under a different name, the Woo Bong. Image: Nesterka, Marine Traffic
But by 2019, it had gone dark. The ship was photographed at sea transferring oil to another ship called the Vifine.
Ship-to-ship transfer between New Konk and Vifine on June 19 2019. Image: UN Security Council.
Ship-to-ship transfer between New Konk and Vifine on June 19 2019. Image: UN Security Council.
The transaction raised alarm bells at the Panel of Experts of the United Nations committee on North Korean sanctions.
Ships that are banned from entering ports because of sanctions often transfer goods at sea, in secret.
New Konk and Vifine were both owned by firms that shared the same address in Hong Kong and were registered the same month. This was no coincidence.
As UN inspectors tracked the ship, New Konk started regularly taking oil from supply ships at sea and that oil would ultimately end up in North Korean ports.
Hiding in plain sight
Hiding from sanction enforcers is serious business.
So New Konk begins its disappearing act.
Generally, ships sailing in international waters are required to have two identification numbers.
One is its International Maritime Organisation number, which stays with the ship throughout its life. It has to be permanently visible on the ship’s hull. But it can be painted over by owners trying to hide the ship's identity.
The second is what's called a Maritime Mobile Service Identity (MMSI) number. It's sort of like a unique phone number issued by a ship’s flag country when a vessel is licensed. Like a phone number, it can change when a ship’s owner changes.
Every ship uses these numbers to broadcast its identity to other ships and ports as it sails.
In October 2019, New Konk stopped using its own IMO and MMSI numbers, and began adopting new identities.
In 2020, for instance, when New Konk was sailing in the East China Sea, it transmitted an MMSI number belonging to another ship called the Mouson 328.
The UN Panel of Experts used satellite imagery to pinpoint a ship with New Konk’s dimensions and shape broadcasting using Mouson 328’s identity in August 2020.
The Mouson 328, docked in the Fujian Yihe Shipyard in October 2019. It looks remarkably similar to the New Konk. Image: Google Earth.
The Mouson 328, docked in the Fujian Yihe Shipyard in October 2019. It looks remarkably similar to the New Konk. Image: Google Earth.
The real Mouson 328, another ship in North Korea’s dark fleet, was somewhere else. It was registered under a new MMSI number, which left New Konk free to use its old one.
It's known in the shipping world as vessel identity laundering.
A fresh makeover
Broadcasting a fake MMSI doesn’t make a ship magically invisible. If a ship is pretending to be another vessel, it needs to look like the original too.
In late 2020, New Konk pulled into the Fujian Yihe Shipyard in eastern China for a paint job. When it arrived, it had a red deck and when it departed, the deck was green.
A red deck in March, a green deck in April. Image: Planet Labs (before), Airbus (after).
And with the paint job came a new name: F.Lonline and another new MMSI.
A long, strange voyage
Remember when New Konk went dark in the East China Sea in 2023?
It wasn't the first time it did this.
It's called “spoofing," when a ship hides its true location, speed and destination from monitoring systems.
Sometimes, the crew will broadcast fake GPS data to make a ship appear to be somewhere else entirely.
It's a dead giveaway when oil tankers "sail" over land.
This map shows the two different journeys of our ship – one real, one fake, in 2023.
Even though the ship's tracking system was turned off, we plotted its real journey using satellite imagery.
In early April, the ship was docked in Sansha Bay near Ningde, China. It's a common staging area for North Korean shadow fleet ships before their voyages.
It then sails north through the Yellow Sea to the North Korean coast.
On July 3, under the cover of darkness, it’s photographed transferring oil to another ship, which then delivers it to an oil terminal in Nampo, North Korea.
The second map shows the journey broadcast from its AIS machine, using fraudulent MMSI numbers and names.
We watched the trickery from March to July 2023. Notice all the random lines and breaks in the paths – that's the ship turning off its tracking or faking its location.
This fake journey shows the ship sailing east into the East China Sea in early April, then south into the Taiwan Strait, then jumping to the South China Sea and then bizarrely back into the East China Sea.
According to its fake identities, it loiters in the Yellow Sea between China and the Korean peninsula for about a week before finally disappearing on the same day the oil transfer took place.
When the ship’s signal reappears shortly after the transfer, it claimed to be in the middle of the Yellow Sea.
New Konk’s last sighting
And this is where we lose its trail.
By 2023, New Konk was already an ancient ship. In the back half of the year, we know it broke down and was moored in North Korean waters waiting for repairs.
We don’t know if it was ever able to sail again.
Most of North Korea's shadow ships are so old and poorly maintained they eventually fade away. The only trace they ever existed is an AIS identity.
The last AIS location broadcast for New Konk was in June 2025 in the South China Sea. But it was almost certainly not our ship, it was likely another ship spoofing, using its IMO number and a fraudulent MMSI.
Targeting a shadowy industry
Cracking down on shadow fleets is as difficult as tracking them.
The companies buying and selling goods to North Korea can be targeted by the UN. The challenge is identifying the true culprits or the countries behind them.
It's also politically fraught. China can block any UN sanctions on Chinese companies with its permanent seat on the Security Council. Indian and Chinese companies are the primary buyers of Russian oil, and sanctioning them would risk worsening tensions with both countries.
Under UN sanctions, states are required to stop North Korean ships from conducting oil transfers in their exclusive economic zones, but China often turns a blind eye to this.
Countries are also legally obligated to stop North Korean shadow fleet ships from docking in their shipyards or ports. But identity laundering offers plausible deniability.
Some countries have resorted to force. US military vessels have stopped and boarded Russian-linked ships transporting oil from Venezuela. European and British naval vessels have recently done the same.
UK forces boarded a Russian tanker in the English Channel on June 14, 2026. Video: UK Ministry of Defence.
UK forces boarded a Russian tanker in the English Channel on June 14, 2026. Video: UK Ministry of Defence.
The reality is no country can police the world's oceans by itself.
We're trying to make it a bit easier though. We're building a database of these ships' movements on a supercomputer and using machine learning to detect patterns that could indicate when vessels are in a suspected shadow fleet.
It's a giant game of cat-and-mouse, with North Korea, Russia and others devising increasingly sophisticated ways to hide their ships, daring other nations to stop them.
The enforcers will always be a step behind.
Disclosures
The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.
Professor of International Relations and Comparative Politics, University of Sydney
Senior Research Fellow, Centre of Maritime Studies, National University of Singapore
Associate Professor, Analytics And Operations, National University of Singapore
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Images
- Ship video: RockfordMedia, Getty Images
- April 2 satellite of New Konk in Sansha Bay: Copernicus Sentinel-2
- 3D tanker model: MJ Lee, SketchFab
- April 8, 2023 satellite of New Konk: Imagery © 2026 Planet Labs
- July 3 2023 imagery of New Konk oil transfer: Member state, United Nations Security Council Panel of Experts, 7 March 2024
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