Two US Navy SEALs are missing off the coast of Somalia, the US Defence Department has said.
They disappeared last Thursday while attempting to board an unflagged dhow which was carrying medium-range ballistic missile parts from Iran to the region.
Although it is believed the weapons were bound for Yemen, the dhow was known to have illegally transferred arms to Somalia.
It is understood one of the SEALs was catapulted into the sea by a strong wave and the second dived into the water attempting to rescue him.
Neither has been seen since.
US Defence officials said SEALs were trained to deal with the conditions and waters in the Gulf of Aden were warm, meaning that exhaustion rather than hypothermia is the main risk.
Ships, drones and helicopters have been deployed in the search for the missing men.
On Friday US Central Command said a search and rescue operation was under way to find the missing sailors, but it did not reveal that they were SEALs.
An official, speaking anonymously, told ABC News that they were on the USS Lewis B. Puller, a Navy expeditionary sea base vessel.
Other members of the US team, who approached the dhow on a special operations combat craft,
Others successfully boarded the dhow, capturing its crew of about a dozen and searching the vessel before confiscating the weapons and sinking the craft.
Over the weekend John Kirby, the administration’s national security spokesman, said the operation was not connected to the strikes against the Houthis.
They were participating in an operation to disrupt the flow of weapons to Yemen, he added.
US officials have accused Tehran of exacerbating the crisis by funnelling military hardware into the region.
The sailors were part of a Naval Special Warfare Command unit, attached to the Bahrain-based Fifth Fleet, which has conducted regular searches of boats in the Gulf of Aden looking for contraband including weapons and drugs.
They were carrying out an operation known as visit, board, search and seizure, or VBSS.
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