Yemen’s Houthi rebels fired two ballistic missiles on Thursday at a Liberian-flagged container ship in the Red Sea, a US defense official said, the latest attack by the rebels as America launches airstrikes targeting them.

The attack happened west of Hodeida, a port city in Yemen long held by the rebels, said the United Kingdom Maritime Trade Operations, a British military group overseeing Mideast waterways. It said the crew and the vessel were safe and the blast came far off the vessel’s starboard side.

The US defense official identified the targeted container ship as the Koi. Its management could not be immediately reached for comment. The official spoke on condition of anonymity to discuss intelligence matters.

The Houthis did not immediately claim responsibility for the assault. The private security firm Ambrey reported Wednesday night that a ship was targeted with a missile southwest of Aden, Yemen, near the Bab el-Mandeb Strait between the Red Sea and the Gulf of Aden. The Houthis claimed that attack also targeted the Koi, though American officials had no immediate information on any attack Wednesday night.