The US Navy's Fifth Fleet said on Wednesday that two of its patrol coastal ships seized a cargo of illicit weapons from a stateless fishing vessel during a flag verification boarding in the North Arabian Sea on Monday.
The shipment consists of approximately 1,400 AK-47 assault rifles and 226,600 rounds of ammunition, the fleet said in a statement.
"The stateless vessel was assessed to have originated in Iran and transited international waters along a route historically used to traffic weapons unlawfully to the Houthis in Yemen," it added.
Direct or indirect supply, sale or transfer of weapons to the Houthi movement violates UN Security Council resolutions and US sanctions.
The vessel's five crew members, who identified themselves as Yemeni nationals, will be returned to Yemen, the fleet said, adding that the US naval forces sank the vessel after removing the crew and illicit cargo.
Guided-missile cruiser USS Monterey (CG 61) seized dozens of advanced Russian-made anti-tank guided missiles, thousands of Chinese Type 56 assault rifles, and hundreds of PKM machine guns, sniper rifles and rocket-propelled grenade launchers from a stateless vessel transiting the North Arabian Sea in May.
A coalition led by Saudi Arabia has been fighting the Iran-aligned Houthi movement since early 2015 after the group ousted the internationally recognized government from Sanaa.
Saudi Arabia and Iran, the region's Sunni Muslim and Shi'ite powerhouses, are bitter rivals but they launched direct talks this year as global powers try to salvage a nuclear pact with Iran and as UN-led efforts to end the Yemen war have stalled.