This advisory supersedes and cancels U.S. Maritime Advisory 2024-004 [and incorporates
information regarding commercially available data on vessel movements, ownership, and
management. Significant updates are bracketed.]

1. References: None.

2. Issue: Regional conflict, military activity, terrorist attacks, and piracy pose significant threats
to commercial vessels operating in the above listed geographic areas as evidenced by recent
Houthi terror attacks and Somali piracy activity. The U.S. government is continually assessing
the maritime security situation in the region to safeguard freedom of navigation, ensure the free
flow of commerce, and protect U.S. vessels, personnel, and interests. The recent standup of
Operation Prosperity Guardian and EUNAVFOR Operation Aspides are examples of U.S. and
international cooperative maritime security operations within this region. The following are
currently deemed to be the most pressing threats to U.S.-flagged and U.S.-affiliated commercial
vessels throughout this region.

3. Guidance:

Houthi Hostile Actions: Commercial vessels transiting the Southern Red Sea, Bab el Mandeb
Strait, and Gulf of Aden continue to be at an elevated risk of terrorism and other hostile actions
from the Houthis. Hostile actions include one-way Unmanned Aerial Vehicle (UAV) attacks;
Unmanned Surface Vehicle (USV) attacks; ballistic and cruise missile attacks; small arms fire
from small boats; explosive boat attacks; and illegal boardings, detentions, and/or seizures. There
have been at least 53 separate Houthi attacks on commercial vessels and one Houthi seizure of a
commercial vessel in these areas, affecting over 55 nations since November 19, 2023. Entities
claiming to be Yemeni authorities have also attempted to divert commercial vessels operating in
these regions from their course. These threats pose both direct and collateral risks to commercial
vessels transiting in international shipping lanes, or otherwise operating in these areas.

[Since January of 2024,] one vessel was sunk by the Houthis in the Bab el Mandeb Strait and one
vessel was struck by the Houthis in the Gulf of Aden, resulting in loss of life and forcing
the crew to abandon the vessel. Both incidents resulted in the issuance of navigation warnings.
Commercial vessels operating in these areas should be vigilant for hazards to navigation caused
by vessels being struck by the Houthis and should be aware of all current navigation warnings.

U.S.-flagged commercial vessels transiting the Southern Red Sea, Bab el Mandeb Strait, and
Gulf of Aden with Automatic Identification System (AIS) transponders on are at increased risk
of targeting by adversarial actors. 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 on and while off, turning AIS off makes it more difficult to track
and accurately target a vessel. [Vessel data, including AIS tracking data, is available from a
variety of commercial web-based companies.] 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. [Limiting AIS data to
only the mandatory fields and omitting the vessel’s next port of call well before entering the Red
Sea and Gulf of Aden should also be considered.]

U.S.-flagged commercial vessels operating in these areas are advised to remain as far as possible
from Yemen’s coastline without compromising navigational safety. Crewmembers should be
especially vigilant when at anchor, operating in restricted maneuvering conditions, loitering, or
proceeding at slow speeds.

U.S.-flagged commercial vessels should coordinate voyage planning with U.S. Naval Forces
Central Command (NAVCENT) Naval Cooperation and Guidance for Shipping (NCAGS) and
consider their recommendations and guidance whenever possible. NAVCENT NCAGS stands a
24-hour watch and has the latest information on the current maritime security threats and the
operational environment in this region.

The route taken through these areas and the timing of the transit remain at the discretion of
individual companies and vessel Masters. [As web-based providers of commercial vessel data
can include information beyond AIS tracking such as prior vessel tracks,] planned routes,
waypoints, and speeds should not be duplicated from prior voyages, when possible. Transiting
these areas during hours of darkness may frustrate efforts to target vessels.

U.S.-flagged commercial vessels are advised to provide hourly positional email updates to the
NAVCENT NCAGS detachment when transiting these areas.

Maritime 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 WiFi routers while
underway in these areas when feasible.

[Web and app-based providers of commercial vessel data could allow access to a vessel’s
ownership and management information, which could be exploited by adversarial actors.]

A missile strike on a Marshall Islands-flagged commercial tanker in the Gulf of Aden on January
26, 2024 resulted in a significant onboard fire. U.S.-flagged commercial vessels carrying
flammable, explosive, or otherwise hazardous cargoes are strongly advised to reconsider transit
through these areas. However, if planning voyages through these areas, vessels should take all
prudent safety precautions, including thoroughly preparing for emergency responses, and
consider carriage of additional safety and damage control preparedness supplies and equipment.

If hailed on VHF by the Houthis, or entities claiming to be Yemeni authorities, and instructed to
divert from their course, U.S.-flagged commercial vessels should ignore the VHF call and
continue their passage if safe to do so. U.S.-flagged commercial vessels that encounter this tactic
are advised not to follow Houthi direction to divert course, as doing so may enhance the ability
of the Houthis to accurately target vessels. U.S.-flagged commercial vessels are advised to
update the NAVCENT NCAGS detachment when this occurs.

If the Houthis seek to board a U.S.-flagged commercial vessel in these areas, the vessel’s Master
should, if the safety of the ship and crew would not be compromised, decline permission to
board, noting that the vessel is proceeding in accordance with international law, as reflected in
the Law of the Sea Convention.

When combined with evasive maneuvering, vessels transiting these areas with armed security
details onboard have successfully deterred boarding by individuals in approaching small craft.
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.

When operating in these waters, U.S.-flagged commercial vessels should always maintain a
proper, vigilant lookout by employing all suitable means in the prevailing circumstances and
conditions. This includes incorporating additional lookouts to ensure a comprehensive
assessment of the situation. See 1972 COLREGS, Rule 5. If U.S.-flagged commercial vessels
observe or hear a suspected UAV or missile or observe a small boat approaching with apparent
hostile intent, crewmembers not needed for the safe navigation and operation of the vessel
should be relocated to a safe space until the threat has passed. Additional precautions should be
taken to ensure small boats are kept at a safe distance whenever possible.

In addition to U.S. Maritime Alerts and this Advisory, interim industry transit advice for the
Southern Red Sea and Gulf of Aden is being distributed by Combined Maritime Forces (CMF).
CMF guidance messages are available on the Maritime Global Security website at
maritimeglobalsecurity.org/geography/goa-etc/.

A new Red Sea/Gulf of Aden Joint Maritime Information Center (JMIC), which is a
collaborative effort between Combined Maritime Forces, the Singapore Navy’s Information
Fusion Center, the Royal Netherlands Navy’s NCAGS, the U.S. Navy Fifth Fleet’s NCAGS, and
others, is now providing Weekly Dashboard and incident specific Info Notes regarding threats
and incidents in this region at [https://www.ukmto.org/indian-ocean/jmic-products].

Iranian Illegal Boarding/Detention/Seizure: Commercial vessels transiting the Persian Gulf,
Strait of Hormuz, Gulf of Oman, and Arabian Sea are at risk of being illegally boarded and
detained or seized by Iranian forces. Recent incidents include the April 2023 Iranian seizure of a
Marshall Islands-flagged vessel in the Gulf of Oman, the May 2023 Iranian seizure of a Panama-flagged
vessel in the Strait of Hormuz, and the January 2024 Iranian seizure of a Marshall
Islands-flagged vessel in the Arabian Sea. Iranian forces attempted to seize one Marshall Islands-flagged
vessel and one Bahamas-flagged vessel in the Gulf of Oman during July 2023, but were
prevented from doing so by U.S. Naval Forces. Iranian forces have utilized small boats and
helicopters during boarding operations and have attempted to force commercial vessels into
Iranian territorial waters.

If hailed by Iranian forces, U.S.-flagged commercial vessels should provide vessel name and flag
state and affirm that they are proceeding in accordance with international law as reflected in the
Law of the Sea Convention.

If Iranian forces seek to board a U.S.-flagged commercial vessel navigating these waters, the
vessel’s Master should, if the safety of the ship and crew would not be compromised, decline
permission to board, noting that the vessel is proceeding in accordance with international law, as
reflected in the Law of the Sea Convention.

If Iranian forces board a U.S.-flagged commercial vessel, the crew should not forcibly resist the
boarding party. Refraining from forcible resistance does not imply consent or agreement to that
boarding.

It is recommended that vessels in the Persian Gulf remain as far as possible from Iran’s territorial
sea without compromising navigational safety. When transiting eastbound in the Strait of
Hormuz, it is recommended that vessels transit close to Oman’s territorial sea.

Industry transit advice for the Persian Gulf, Strait of Hormuz, and Gulf of Oman was issued on
November 9, 2023, and can be found on the Maritime Global Security website at
maritimeglobalsecurity.org/geography/goa-etc/.

Piracy and Armed Robbery Against Ships: Recent cases of piracy pose a threat to commercial
vessels operating in the Gulf of Aden, Arabian Sea, Somali Basin, and Indian Ocean. Since
November 2023, there have been four boarding/hijacking incidents, representing the first such
attacks against commercial shipping in the region since March 2017. Pirates may utilize captured
fishing vessels as motherships to target vessels operating hundreds of miles from the coast of
Somalia. In November 2023, one Liberian-flagged vessel was boarded in the Gulf of Aden; in
December 2023, one Malta-flagged vessel was hijacked in the Arabian Sea; and in January 2024,
one Liberia-flagged bulk carrier was boarded in the Indian Ocean. Specific case details are
available on the Office of Naval Intelligence's weekly "Worldwide Threat to Shipping" product
at https://www.oni.navy.mil/ONI-Reports/Shipping-Threat-Reports/Worldwide-Threat-to-
Shipping/.

The Best Management Practices to Deter Piracy and Enhance Maritime Security in the Red Sea,
Gulf of Aden, Indian Ocean and Arabian Sea (BMP5), and Maritime Global Security website at:
https://www.maritimeglobalsecurity.org should be consulted prior to operating in those
geographic waters.

Transit by yachts and privately owned sailing vessels through these waters is hazardous and may
result in capture. The U.S. Government advises against all operation of yachts and pleasure craft
in these areas.

American citizens abroad should inform the nearest U.S. embassy or consulate of their plans to
transit the area and/or update their information via the Smart Traveler Enrollment Program
(STEP) at: https://step.state.gov/step/. Yachting guidance can be found at: https://onshore.
mschoa.org/reference-documents/advice-for-sailing-vessels.

UAVs: Outside of the Southern Red Sea, Bab el Mandeb Strait, and Gulf of Aden, UAV attacks
also pose a threat to commercial vessels in the Persian Gulf, Strait of Hormuz, Gulf of Oman,
and Arabian Sea. The most recent attacks were on a Malta-flagged vessel in the Arabian Sea in
November 2023, and on a Liberian-flagged vessel in the Arabian Sea in December 2023.

If U.S.-flagged commercial vessels observe or hear a suspected UAV, crewmembers not needed
for the safe navigation and operation of the vessel should be relocated to a safe space on the
vessel until the threat has passed.

Limpet Mines: Limpet mines have been used to damage commercial vessels on multiple
occasions in recent years and are primarily a threat to commercial vessels in the Persian Gulf,
Strait of Hormuz, and the Gulf of Oman. Limpet mines, or similar improvised explosive devices,
can be attached to vessel hulls, above or below the waterline, via swimmers or small boats, while
a vessel is berthed, at anchor, or underway.

When operating in these waters, U.S.-flagged commercial vessels should maintain a close
lookout and remain vigilant for suspicious activity to include the approach of swimmers or small
boats. Close attention should be given to the vessel’s waterline, especially at slow speeds, at
anchor, and when moored.

If a mine has been, or was attempted to have been, attached to a vessel, crewmembers not needed
for the safe navigation and operation of the vessel should be relocated to a safe space on the
vessel until the threat has passed.

U.S.-flagged commercial vessels operating in these waters are advised to exercise caution,
review security measures, and monitor VHF Channel 16. To afford best protection in the region,
U.S.-flagged commercial vessels are also advised to:

In the event of any attack, incident, or suspicious activity, immediately:

Activate the Ship Security Alert System

Contact the U.S. Fifth Fleet Battle Watch

Contact UKMTO

Simultaneously register with both the United Kingdom Maritime Trade Office (UKMTO) and
the International Maritime Security Construct (IMSC) watch 24 hours prior to entering the
Indian Ocean Voluntary Reporting Area by sending UKMTO and IMSC, via a single e-mail, the
Initial Report from Annex D of (BMP5). Include the estimated times of arrival at the Suez
Canal, Bab el Mandeb Strait (BAM), and Strait of Hormuz (SoH) in line 10 of the report and add
line 14 for comments as needed (e.g., speed restrictions or other constraints, anticipated time of
entering/exiting the SoH Traffic Separation Scheme; an outline of the navigation plan for
operating in the SoH and Persian Gulf, etc.). Utilize other reports included in Annex D of BMP5
as necessary.

Vessels operating in this area are advised to include both NAVCENT NCAGS and the IMSC
watch on all updates or incident report emails. By including both as addressees on each email,
awareness will be enhanced without creating an additional reporting burden.

Conduct a pre-voyage risk assessment and incorporate appropriate protective measures into
vessel security plans.

The Maritime Global Security website at https://www.maritimeglobalsecurity.org/ offers
industry issued best practices and guidance to mariners by geographic region and provides
contact and subscription information for regional maritime security reporting centers,
particularly in high risk-areas.

Answer all VHF calls from coalition navies. Vessels should be aware that U.S. and other
coalition naval forces may conduct maritime awareness calls, queries, and approaches to ensure
the safety of vessels transiting these listed waters.

Due to the risks of piracy, kidnapping, hijacking, and robbery while operating within U.S. Coast
Guard designated High-Risk Waters (HRW), U.S.-flagged commercial vessels are required to
comply with the Guidelines for U.S. Vessels Operating in High-Risk Waters contained in U.S.
Coast Guard Maritime Security Directive 104-6 (Rev 8) and comply with their Coast Guard
approved Vessel Security Plan annex on counter piracy. The U.S. Coast Guard Office of
Commercial Vessel Compliance (CG-CVC) announced in the Federal Register in August 2021
the availability of Revision 8 to Maritime Security (MARSEC) Directive 104–6. U.S. vessel
owners and operators who needed to act under previous versions of MARSEC Directive 104–6
should immediately contact their local Coast Guard Captain of the Port or District Commander
for a copy of Revision 8.

Per 33 CFR 101.305, report all suspicious activities, breaches of security, and transportation
security incident events involving U.S. vessels or persons to the U.S. Coast Guard National
Response Center. Additional U.S. Coast Guard port specific requirements may be found in Port
Security Advisory 1-22 at
https://www.dco.uscg.mil/Portals/9/DCO%20Documents/InternationalPortSecurity/Port%20Sec
urity%20Advisory/PSA%20%201-
22%20Remove%20Cote%20d'Ivoire.pdf?ver=6DzYOEsWAJQVh7ld4c0ycQ%3d%3d.

4. Contact Information:

a) Fifth Fleet Battle Watch: cusnc.bwc@me.navy.mil or + 973-1785-3879.

b) NAVCENT NCAGS: +973-1785-0033 (Primary/Watch Desk), +973-3940-4523 (Alternate), or
m-ba-navcent-ncags@us.navy.mil.

c) IMSC: m-ba-imsc-bwc@us.navy.mil or +973-1785-8412/8192/8193. IMSC organizational
information is available at https://www.imscsentinel.com/.

d) UKMTO: watchkeepers@ukmto.org or +44 (0) 2392 222060. UKMTO advisories and
warnings are available at https://www.ukmto.org/.

e) U.S. Coast Guard National Response Center: +1-800-424-8802.

f) USCG NAVCEN: www.navcen.uscg.gov/contact/gps-problem-report or +1-703-313-5900.

5. Cancellation of Prior Advisories: This message supersedes and cancels U.S. Maritime
Advisory 2024-004 and will automatically expire on October 15, 2024.

For maritime industry questions about this Advisory, contact the Global Maritime Operational
Threat Response Coordination Center at GMCC@uscg.mil. Supplemental information about
U.S. Maritime Alerts and Advisories, including subscription details, may be found at:
https://www.maritime.dot.gov/msci. Feedback provided by U.S. maritime industry stakeholders
regarding the U.S. Maritime Advisory System has greatly supported the USG in pursuing
continued enhancements to this system. Feedback to MARADSecurity@dot.gov is always
welcome.