Also this from the U.S. Maritime Administration:
2019-012-Persian Gulf, Strait of Hormuz, Gulf of Oman, Arabian Sea, Red Sea-Threats to Commercial Vessels by Iran
This revised advisory cancels U.S. Maritime Advisories 2019-004 and 2019-008.
1. References: U.S. Maritime Alerts 2019-004A, 2019-003A, 2019-002A, and 2019-001A.
2. Issue: Heightened military activity and increased political tensions in this region continue to pose serious threats to commercial vessels. Associated with these threats is a potential for miscalculation or misidentification that could lead to aggressive actions. Vessels operating in the Persian Gulf, Strait of Hormuz, and Gulf of Oman may also encounter GPS interference, bridge-to-bridge communications spoofing, and/or other communications jamming with little to no warning.
Since May 2019, the following maritime incidents have occurred in this region:
- Six attacks against commercial vessels (see U.S. Maritime Alerts 2019-002A and 2019-003A);
- Shoot-down of U.S. Navy remotely piloted aircraft over international waters;
- Attempted at-sea interdiction of Isle of Man-flagged M/V BRITISH HERITAGE;
- Seizure of ex-Panama-flagged M/V RIAH;
- Seizure of U.K.-flagged M/V STENA IMPERO (see U.S. Maritime Alert 2019-004A); and
- Detention and subsequent release of Liberian-flagged M/V MESDAR (see U.S. Maritime Alert 2019-004A).
In at least two of these incidents, vessels reported GPS interference. One vessel reportedly shut off its Automatic Identification System (AIS) before it was seized, complicating response efforts. Vessels have also reported spoofed bridge-to-bridge communications from unknown entities falsely claiming to be U.S. or coalition warships.
The United States is committed to safeguarding freedom of navigation, the free flow of commerce, and the protection of U.S. vessels and personnel in this region.
3. Guidance: The international community, including the United States, continues maritime security operations within this region. Vessels operating in this area are advised to review security measures, ensure AIS is transmitting at all times, and monitor VHF Channel 16.
a) To afford best protection in the region, U.S. flagged commercial vessels are encouraged to:
- Simultaneously register with both the United Kingdom Maritime Trade Office (UKMTO) and U.S. Fifth Fleet Naval Cooperation and Guidance for Shipping (NCAGS) Watch when entering the Indian Ocean Voluntary Reporting Area (VRA) by e-mailing them the Initial Report from Annex D of Best Management Practices to Deter Piracy and Enhance Maritime Safety in the Red Sea, Gulf of Aden, Indian Ocean and the Arabian Sea (BMP5).
- Provide transit plans for the Strait of Hormuz (SoH) and Persian Gulf (PG) to UKMTO and U.S. Fifth Fleet NCAGS via a single e-mail, including the time of entering/exiting the SoH Traffic Separation Scheme, an outline of the navigation plan for operating in the SoH and PG, and speed restrictions or other constraints.
- In the event of any incident or suspicious activity, call UKMTO or the U.S. Fifth Fleet Battle Watch and activate the Ship Security Alert System immediately.
- Answer all VHF calls from coalition navies.
- Utilize other reports included in Annex D of BMP5 as necessary, including both UKMTO and Fifth Fleet NCAGS on each of these reports.
b) All 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 the Persian Gulf, Strait of Hormuz, Gulf of Oman, and Arabian Sea. If a U.S. flag commercial vessel suspects it is being hailed from a source falsely claiming to be a U.S. or coalition naval vessel, the U.S. Fifth Fleet Battle Watch should be immediately informed.
c) If hailed by Iranian forces, U.S. flag commercial vessels should provide vessel name, flag state, and affirm that they are proceeding in accordance with international law as reflected in the Law of the Sea Convention. The master should immediately inform the U.S. Fifth Fleet Battle Watch.
d) If Iranian forces seek to board a U.S. flag commercial vessel navigating these waters, the ship’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, and immediately inform the U.S. Fifth Fleet Battle Watch.
e) If Iranian forces board a U.S. flagged commercial vessel, the vessel should immediately contact the U.S. Fifth Fleet Battle Watch. The crew should not forcibly resist the boarding party. Refraining from forcible resistance does not imply consent or agreement to that boarding.
f) The Maritime Global Security website at https://www.maritimeglobalsecurity.org/ offers industry issued best practices, including BMP5, and guidance to mariners by geographic region and provides contact and subscription information for regional maritime security reporting centers.
g) Vessels operating in this area are advised to establish contact with both UKMTO and the U.S. Fifth Fleet NCAGS Watch, and to include both on all update or incident report emails, as detailed above. By including both as addressees on each email, awareness will be enhanced without creating an additional reporting burden.