In just days, Yemen’s Houthi rebels have begun a new, more violent campaign of attacks targeting ships in the Red Sea, sinking two of them and killing some of their crew.

The UN's Yemen envoy has expressed serious concern over the situation in the Red Sea, and warned of potential environmental damage after two Houthi attacks on commercial vessels.The incidents mark the first such attacks since Washington announced a truce with the Iran-backed rebel group in May.