New U.S. Maritime Advisory: Turn off AIS in Houthi risk area

Although there have been no Houthi attacks on commercial ships since the Israel-Gaza ceasefire agreement in October 2025, a new U.S. Maritime Advisory warns that the Houthis continue to pose a threat to U.S. assets, including commercial vessels, in the Red Sea, Bab el Mandeb Strait, Gulf of Aden, Arabian Sea, and Somali Basin region.

Potential hostile actions include one-way unmanned aerial vehicle (UAV) attacks; unmanned surface vehicle (USV) attacks; unmanned underwater vehicle (UUV) attacks; ballistic and cruise missile attacks; small arms fire from small boats; explosive boat attacks; and illegal boardings, detentions, and/or seizures.

GUIDANCE

“U.S.-flagged commercial vessels transiting the Red Sea, Bab el Mandeb Strait, Gulf of Aden, Arabian Sea, and Somali Basin with Automatic Identification System (AIS) transponders on are at increased risk of targeting by adversarial actors,” says the advisory. “U.S.-flagged commercial vessels operating in these areas are strongly advised to turn off their AIS transponders, unless vessel Masters believe that doing so would compromise the safety of the vessel. The International Convention for the Safety of Life at Sea (SOLAS), Chapter V, regulation 19.2.4, and IMO Assembly Resolution A 29/Res.1106 permit vessel Masters to turn AIS off if they ‘believe that the continual operation of AIS might compromise the safety or security of their ship, or where security incidents are imminent.’ See also 33 CFR § 164.46(d)(2)(v). While vessels have been attacked by the Houthis while AIS transponders were either on or off, turning AIS off makes it more difficult to track and accurately target a vessel. Minor variations to course and speed may further complicate Houthi targeting. It should be noted that additional onboard systems that transmit commercial data might also be used for tracking to include reefer temperatures and weather. Adherence to all flag State and international requirements and guidance regarding operation of AIS, and the safe navigation of the vessel, remains the responsibility of individual companies and vessel Masters.”

The advisory also says that operators are advised to alert their crews to the fact that all electronic signals from their vessels pose a risk to maritime operations and are strongly advised to secure Wi-Fi routers while underway in these areas when feasible.

The advisory notes that vessels transiting these areas with armed security details onboard have successfully deterred boarding by individuals in approaching small craft and USV attacks. The decision whether to embark a contracted armed security detail and assessment of associated risks is the responsibility of individual companies and vessel Masters, who are responsible for establishing use of force guidance and pre-planned responses for vessels carrying contracted armed security details.

If Houthis board a U.S.-flagged commercial vessel without a contracted armed security detail onboard, the crew should not forcibly resist the boarding party. Refraining from forcible resistance does not imply consent or agreement to that boarding.

• Much more in the full advisory HERE