Yemen's Houthi militants said on Monday they attacked two US ships, Sea Champion and Navis Fortuna, in the Gulf of Aden.
"The targeting operation was carried out with a number of appropriate naval missiles, and the casualties were accurate and direct, thanks to God," the group's military spokesman Yahya Sarea said in a statement.
The United Kingdom Maritime Trade Operations (UKMTO) agency received a report on Monday of an incident 100 nautical miles east of Yemen's port of Aden.
The UKMTO added that authorities were investigating the incident and no further details were immediately provided.
Unmanned underwater vessels
The decision by the Houthis to use unmanned “underwater vessels” presents a new danger. The group already used ballistic missiles, and small watercraft as well as helicopters in its attacks on ships. CENTCOM says that its “actions will protect freedom of navigation and make international waters safer and more secure for US Navy and merchant vessels.”
However, there are questions about whether the Houthis can and will be deterred. The group was pressed by Iran in October to join Hezbollah and Hamas in initiating attacks on Israel. In addition, Iran operationalized militias in Iraq and Syria to attack US forces.
As such, the Houthis are a key frontline force for Iran now, which has required the Houthis to continue to act against shipping. Even a few attacks a month are apparently enough to deter some shipping companies from using the important shipping lane via the Red Sea.
Seth J. Frantzman contributed to this report.