The parts, which were seized in a Navy SEAL operation Thursday in international waters near the coast of Somalia, consisted of both "Iranian-made ballistic missile and cruise missiles components," US Central Command said in a statement on X.

The statement revealed that two SEALS already reported as lost at sea were involved in the mission, with "an exhaustive search" still underway, according to US Central Command chief Michael Kurilla.

"This is the first seizure of lethal, Iranian-supplied advanced conventional weapons (ACW) to the Houthis since the beginning of Houthi attacks against merchant ships in November 2023," CENTCOM said.

"Seized items include propulsion, guidance, and warheads for Houthi medium range ballistic missiles (MRBMs) and anti-ship cruise missiles (ASCMs), as well as air defense associated components," it added.

"Initial analysis indicates these same weapons have been employed by the Houthis to threaten and attack innocent mariners on international merchant ships transiting in the Red Sea," it said.

The weapons parts were seized from a dhow -- a traditional masted sailing vessel -- with 14 crewmembers whose disposition was "being determined in accordance with international law."

The boat itself was deemed unsafe and sunk.

Announcement of the seizure comes after US and British forces on Friday hit scores of rebel targets across Yemen, a move triggered by the rebels' repeated attacks on shipping.

Attacks by and against the Huthis, part of the "axis of resistance" of Iran-aligned groups, have raised concerns about violence spreading in the region from the Gaza war.

"It is clear that Iran continues shipment of advanced lethal aid to the Houthis. This is yet another example of how Iran actively sows instability throughout the region," Kurilla said, adding that Tehran's actions violated both a UN security resolution and international law.

The Huthis say their attacks on Red Sea shipping are in solidarity with Gaza, where Iran-backed Hamas militants have been at war with Israel for more than three months.

Around 12 percent of global trade normally passes through the Bab al-Mandeb Strait, the Red Sea's entrance between southwest Yemen and Djibouti, but the rebel attacks have caused much shipping to be diverted thousands of miles around Africa.