A missile attack by Yemen’s Houthi rebels damaged a ship in the Red Sea on Monday, authorities said, the latest assault in their campaign against shipping in the crucial maritime route.

The attack happened off the coast of Mokha, Yemen, the British military’s United Kingdom Maritime Trade Operations center said. The ship was damaged in the attack, the UKMTO said, though its crew was safe and heading to its next port of call. The agency urged vessels to exercise caution in the area.

There was “an explosion in close proximity to a merchant vessel,” the UKMTO said. “Vessel and crew are reported safe.”