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.

Houthi rebels in Yemen have launched a violent new wave of attacks on ships in the Red Sea, sinking two vessels and killing crew members.

The attack on the Eternity C, which killed at least three of the crew, represents the most serious assault carried out by the Houthis in the crucial maritime trade route.