“Operations in the Red and Arabian Seas, Bab al-Mandab Strait, and the Gulf of Aden are continuing, escalating, and effective,” Abdul Malik al-Houthi added in a televised speech. He gave no details of the submarine weapons.

Ships owned by individuals or entities in Israel, the U.S. and U.K. or sailing under their flags are banned from the Red Sea, Gulf of Aden and Arabian Sea, Thursday’s notices said.

“The Humanitarian Operations Center was established in Sanaa to coordinate the safe and peaceful passage of ships and vessels that have no connection to Israel,” a senior Houthi official told Reuters on Thursday.

No ships have been sunk nor crew killed during the Houthi campaign. However there are concerns about the fate of the UK-registered Rubymar cargo vessel, which was struck on Feb. 18 and its crew evacuated.