Yemen's Tehran-backed Houthi movement fired missiles and drones at Saudi Arabian cities and energy facilities on Tuesday, part of a wider regional escalation more than six months into the U.S. war with Iran.

Saudi Arabia promises firm retaliation after Houthi strikes injure 73 and disrupt energy facilities in southern cities.

Houthi rebels in Yemen have accused Saudi Arabia of striking a prison in the north, escalating tensions between the Iran-backed group and Saudi-backed Yemeni forces.

Pakistan Defence Minister Khawaja Asif warned that the Makkah Defence Alliance with Saudi Arabia and Turkiye could become operative if Houthi attacks spill into Saudi Arabia. He said aggression against one member would be treated as an attack on all under the pact.

Iran threatened the United States with "economic warfare" on Tuesday and said it had fired an advanced missile at U.S. warships, underscoring the risks of further escalation in ​the war only days after both sides traded blows again.

SAUDI Arabia has threatened to hit back after Iran-backed Houthis pounded the state with their worst attack in years. The barrage of missiles from Houthi rebels set oil facilities ablaze and