Washington (CNN) -- A cache of weapons seized from a ship off the coast of Yemen had markings that indicate they came from Iran, a U.S. official said Tuesday.
The markings on those weapons -- which included surface-to-air missiles, potent explosives and rocket-propelled grenades -- indicate they came from Iranian Revolutionary Guard Corps facilities, said the official, who declined to be identified because of the sensitive nature of the information.
The weapons were believed to be headed for Shiite Muslim insurgents in Yemen, the official told CNN. The country's government has fought periodic battles against the Houthis, a Shiite rebel movement in northern Yemen, in a conflict seen as both separatist and sectarian.
Yemen accused Shiite-majority Iran of supporting the Houthis during their last major revolt, in 2009, which saw Sunni-led Saudi Arabia launching airstrikes against suspected Houthis on its side of the border. Iran denied the allegations and criticized the Saudi strikes.
Yemen's government announced the arms seizure on Monday, saying the ship had been boarded in Yemeni territorial waters in the Arabian Sea on January 23. The American destroyer USS Farragut was working with Yemeni authorities when they spotted the vessel in question, an Obama administration official said Monday.
The ship had several flags onboard, but no reliable documentation showing where it came from, the official added.
The firepower included anti-aircraft missiles, C4 military-grade explosives, ammunition and bomb-making equipment such as circuits, remote triggers and various handheld explosives, the Yemenis said. The vessel carried a crew of eight Yemenis, they said.
The Obama administration official described the seizure as a joint operation, and said U.S. forces joined their Yemeni counterparts in boarding the suspect boat.