Report: Ships Make Novel Use of AIS to Ward Off Attacks by Houthis

warning messages on AIS
Ships transiting the Red Sea are sending out messages to ward off attacks (UKMTO map of the danger zone)

Published Dec 28, 2023 4:03 PM by The Maritime Executive


With the security situation remaining very volatile in the Red Sea and around the Bab al-Mandab Strait, ships and their owners/operators are looking for any means to improve security. Many ships have chosen to reroute away from the danger while it also appears some are trying to use a novel means of communication to speak indirectly to the Houthis to ward off potential attacks. 

Since launching the attacks, the Houthi rebels in Yemen have vowed to target any ships owned by Israeli interests or trading with Israel. U.S. officials have said that over 100 drones and missiles have been launched against merchant shipping in the region and an analysis of the individual attacks in many cases has found either a clear linkage to Israeli interest or suspected associations. The Houthis appear to be using the Internet and searching databases to identify at least some of their targets.

Initially after the seizure of the car carrier Galaxy Leader, and with reports of small boats attempting to hail or board ships, the owner/operators responded by increasing onboard security. There were several reports of armed guards firing warning shots at small boats when they came too close.

Normally the vessel’s Automatic Identification System is used to post information about the ship’s destination, direction, and speed. Occasionally it is used to warn of dangers. It is common to see a ship listed as “not under command,” when it is experiencing a mechanical problem to warn ships not to approach. A vessel between contracts often posts a message “awaiting orders” to say it is anchored or drifting aimlessly.



Now, however, ships have started using their AIS to communicate indirectly with the rebels. When the primary fear was boardings, ships began displaying messages saying “armed guard onboard.” Several tankers transiting the Red Sea today are showing that message as their destination.

TankerTrackers.com highlights in its posting on X (formerly Twitter) that it identified a new message attempting to say we are not involved in your fight. The tracking and analytics company detected several vessels using a new tactic, posting a message they called “interesting.”




The Kriti State, a 76,500 dwt crude oil tanker registered in Liberia and sailing from Novorossiysk, Russia, was the first vessel TankerTrackers.com detected using a message to say it was not associated with Israel. TankerTrackers.com posted an image to X showing the tanker displaying the message “VSL No Cntact Israel.” The tanker is owned and managed out of Greece.

It might have been a one-off, but an hour later TankerTrackers.com posted another image on X showing a similar message from the Xin He Lu 1, a containership registered in Liberia. At last check, the 46,350 dwt vessel still has that message on its AIS display. The 46,350 dwt/3429 TEU containership owned and managed out of China is also outbound from Novorossiysk, Russia, but a decade ago appears to have operated under charter to the Israeli shipping company Zim. TankerTrackers.com reports it also spotted a third vessel displaying the same message earlier today.

It is not clear if the message is reaching the intended target and if this is a coincidence or a planned effort to try and ward off attacks. Earlier this week, the destroyer USS Laboon took down 12 one-way attack drones, three anti-ship ballistic missiles, and two land attack cruise missiles in 10 hours, all fired by the Houthis in the Southern Red Sea. On Thursday, USS Mason shot down one drone and one ballistic missile, according to U.S. Central Command.