The cost of insuring commercial ships that sail past Yemen’s Houthi militants surged after the rebels sank two ships and killed sailors this week, underscoring how the attacks have revived risk in the crucial waterway.

Rescuers pulled three more crew members and a security guard alive from the Red Sea on Thursday, maritime security sources said, a day after Houthi militants sank the Greek ship Eternity C and said they were holding some of the crew still missing.

Crew members aboard a Liberian-flagged ship set ablaze by a series of attacks in the Red Sea abandoned the vessel Sunday night as it took on water, marking the first serious assault in the vital corridor for trade after a monthslong campaign by Yemen‘s Houthi rebels there.

Israel carried out it first strikes against Houthi targets in Yemen since the Israel-Iran ceasefire, attacking ports and a power plant around midnight local time Sunday night into Monday morning.