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.
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.
But by 2019, it had gone dark. The ship was photographed at sea transferring oil to another ship called the Vifine.
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.
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 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.
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.
And with the paint job came a new name: F.Lonline and another new MMSI.
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.
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.
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.