Iran shipments to Houthis a masterclass in AIS manipulation
- rorykevinproud
- Jul 17
- 2 min read
17 July 2025 Lloyd's List
The Houthis have a robust weapons supply chain and there are limited options for interrupting these networks
Vessels delivering cargo from Iran fly fraudulent flags and hide IMO numbers
Most arrivals to Houthi-controlled ports call at Djibouti first, suggesting at least initial compliance with a UN mechanism which helps enforce the arms embargo
Disruption of smuggling supply chain extremely difficult says experts
Despite US and Israeli air strikes on Houthi bases and reports of some seizures of dhows carrying weapons heading into Houthi territory, security analysts have been warning that weapons and components have continued to flow into Yemen.
Intelligence reports suggest that the Houthis continued to restock critical components to assemble ASBMs locally, but also managed to receive a number of additional munitions.
That restocking process has been happening for several months. The Houthis have been receiving what a UN panel of experts described as an ‘unprecedented’ amount of military materiel, a significant amount of which is being moved through the ports of Hodeidah and Saleef.
A Lloyd’s List investigation gives a small insight into this opaque supply chain, revealing the sophisticated manipulation used to complicate efforts to track shipments and difficulties in disrupting these operations.
In its 2024 report, the UN panel of experts identified six vessels for calling at Houthi-controlled ports without receiving clearance from the UN Verification and Inspection Mechanism.
UNVIM is a body that monitors and inspects cargo bound for Yemeni ports not under the internationally recognised government’s control. Its purpose is to facilitate trade into these ports while helping to uphold the arms embargo.
Comoros-flagged aggregates carrier Almas (IMO: 8864957), can be tracked using Automatic Identification System data calling at Hodeidah in October 2023.
Almas did not stop in Djibouti, where UNVIM is based and inspections are carried out, after sailing from Iran.
The entire voyage can be viewed using AIS positions, but an assessment of the messages reveal the efforts taken to conceal the ship’s identity and movements.
Almas never actually transmits its International Maritime Organization number over the course of the voyage. This is because the ship stopped using a class A AIS transponder in October 2022, transmitting only through a class B system from that point onwards.
Class B transponders are designed for smaller vessels. They generally have a smaller data package, with many of the data fields being empty or reporting “not available”, including the IMO number. The data is also not reported as often as class A.
“It’s kind of like pulling up your hood and trying to walk through a busy crowd,” says Lloyd’s List Intelligence data scientist Thomas Spriggs.
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