The Houthis and their Iranian allies employ radar and satellite communications to target commercial vessels and US and UK warships. The US should consider jamming Iranian radars used by the Houthis and working with commercial satellite operators to shut down access to communications guiding Houthi missiles and drones.
The automatic identification system (AIS) needs to be changed to confuse the Houthis and Iranians. The Houthis have a large arsenal of drones, cruise missiles, and ballistic missiles, with nine types: Hudhud-1, Raqib, Rased, Sammad-1, Qasef-1, Qasef-2K, Sammad-2, Sammad-3, and Wa-eed-2. The Houthis use Qasef-1, Qasef-2, or Shahed-136 drones to target commercial ships and US warships. These drones, similar to Iran’s kamikaze weapon, are heavily used in Ukraine, but can be jammed. Understanding their targeting methods is crucial for accurate strikes.
The Houthis and Iranians are using the Global AIS (Aerospace Identification System) to track ships in the Red Sea, Persian Gulf, and Indian Ocean. AIS transponders are used by commercial vessels over 300 tons, broadcasting location, speed, and vessel name every two to 10 seconds. However, AIS is not as accurate as radar, with a recent study showing that AIS transponder information is off by 97.72 meters (or around 320 feet), meaning it may not ensure a UAV or cruise missile hits its target.
AIS track can interpret radar information, allowing targets to be identified, passed to a radar station, and followed by the radar. This allows the Houthis or Iranians to know their target’s location in near real-time. The next challenge is communicating with cruise missiles or drones, as direct radio communications become difficult as targets move further away from the shoreline. FPV drones can be operated over a distance of 8 to 10 kilometers from the operator, but the Houthis have already attacked a merchant ship 177 kilometers from where the drone was launched.
In December 2023, Ukrainians recovered a crashed Shahed-136 drone, now manufactured in Russia as Geran-2 (Geranium-2). The drone was unique in that it was equipped with an Alcatel internet modem and a SIM card belonging to a Ukrainian 4G cellular service called Kyivstar. The recovered drone may have had a camera, allowing it to hit moving targets and transmit imagery back to operators on the internet, allowing remote operation and accurate attacks.
This finding is similar to the recovery of Iranian drone parts that hit the Campio Square commercial ship on February 10, 2023. The part recovered was a SIM card for Iridium Communications, a global satellite communications company. Iridium offers voice and data communications services to customers worldwide, and SIM cards for Iridium satellites are widely available. Iridium is popular for maritime use and military operations, as it is particularly popular for maritime connectivity. The debate on the Shahed’s compatibility with Ukrainian cellular capability remains.
The Houthi rebels in the Red Sea have been using Iridium communications for Kartograf UAVs, designed for panoramic aerial photo and video recording. These drones can be used for reconnaissance, correcting artillery fire, or missile strikes. If the Houthi incorporate Iridium SIM cards and modems into their Shahed-136 drones, they would have a better chance of accurately targeting commercial vessels. As long as their coastal radars were operational, the Houthis could also target US military ships, provided they could find them.
However, US military ships do not use them in combat areas and none are currently operating with AIS in the Red Sea. Without coastal radars, the Houthis would need alternative ways to locate US warships. They could be getting live feeds from the Iranian spy ship, the cargo ship Behshad, or the Iranian warship IRIS Alborz, which crossed through the Bab el-Mandeb strait on January 11, following a joint US-UK strike on the Houthis. These ships could replace the radars the Houthis have lost.
The US should focus on localizing Houthi attacks and degrading their targeting capability. This could involve jamming Iranian frigates and spy ships’ radars, which may feed real-time targets to the Houthis. Additionally, interdicting satellite communications supporting Houthi and Iranian operations, working with Iridium, could be a more effective strategy. Shutting down these communications would take away valuable assets like radars targeted with Tomahawk missiles. For merchant ships, turning AIS off and on at intervals could help thwart Houthi targeting.
