Yemen's Houthi leader Abdul-Malik al-Houthi threatened Saudi Arabia with "full escalation," hours before Riyadh announced a new maritime defence coalition designed to counter the Iran-backed group's expanding campaign against Red Sea shipping. Saudi Arabia will serve as the founding and leading state and will host the coalition's permanent headquarters, joint command and operational centre. The EU, which already runs the Aspides naval protection mission in the Red Sea, sent a delegation but did not sign the deal. Blockade and tanker attackThe Houthis announced last week a naval blockade against Saudi Arabia on 20 July. Advertisement AdvertisementAdvertisement AdvertisementRiyadh has since launched air strikes on Houthi military positions and infrastructure in Hodeidah, Yemen's main Red Sea port.