( CNN ) -- Yemeni authorities working with the U.S. Navy intercepted a ship carrying a `` substantial '' cache of `` illegal arms '' such as surface-to-air missiles , potent explosives and rocket-propelled grenades , a U.S. official and Yemen 's government said Monday . The incident took place in Yemeni territorial waters in the Arabian Sea last Wednesday , according to a statement issued five days later from Yemen 's embassy in Washington . The crew of the USS Farragut , a Naval destroyer , was working with Yemeni authorities when they spotted the vessel , said an official in the Obama administration . The ship had several flags onboard , but no reliable documentation showing where it came from , the official added Monday . After the ship was intercepted , Yemeni coast guard officers boarded it and `` found a large cache of illegal arms , '' according to the Yemeni embassy 's statement , which was also posted on the website of the Arabian country 's state-run SABA news agency . The firepower included anti-aircraft missiles , C4 military-grade explosive , ammunition and bomb-making equipment such as circuits , remote triggers and various handheld explosives , the Yemeni statement said . There were eight Yemeni crew members aboard the vessel . The Obama administration official described the effort as a joint operation , and said U.S. forces joined their Yemeni counterparts in boarding the suspect boat . High-ranking AQAP leader killed . U.S. drone strike kills six in Yemen . CNN 's Barbara Starr reported this story from Washington , and Greg Botelho wrote it from Atlanta . CNN 's Hamdi Alkhshali contributed to this report .
Yemen and U.S. authorities work together in intercepting a ship in the Arabian Sea . The United States has been carrying out drone strikes against suspected Al Qaeda militants on Yemeni soil since 2009. The vessel had surface-to-air missiles , explosives and more aboard , Yemen 's embassy says .