The Houthis, a rebel group based in Yemen who are backed by Iran, have stepped up attacks on commercial ships in the Red Sea, targeting ships to pressure Israel amid its conflict with Hamas in Gaza. The Houthis seized Yemen's capital Sanaa in 2014 and have been fighting the Yemeni government in a civil war since then. The Houthis attacked several ships on Tuesday. A US destroyer responded by shooting down Houthi drones. The US has formed a new international task force called Operation Prosperity Guardian involving 10 countries to coordinate security and counter the Red Sea attacks.