Yemen's Houthis vowed on Wednesday to press on with attacks on airports and oil facilities in Saudi Arabia, a day after a strike that sources said caused extensive damage to the headquarters of oil giant Saudi Aramco.
The Houthis said the threatened locations were legitimate targets and described their attacks as retaliation for Saudi strikes on Yemen, threatening to escalate a conflict reignited by the US-Iran confrontation in the Gulf.
Saudi Arabia has faced widening Houthi strikes over the past week, including an attack on King Khalid International Airport in Riyadh on Saturday that killed 13 people.
Tuesday night's attack on Saudi Aramco's base in the eastern city of Dhahran caused a fire that spread across several floors, three people with knowledge of the matter told Reuters. The Saudi energy ministry had said the strike caused a limited fire.
Operations at Aramco were continuing normally, with employees working from home, according to two of the sources. Aramco did not immediately reply to a Reuters request for comment.
Saudi-led forces say they intercept missile
The escalating conflict has dealt a blow to Saudi Crown Prince Mohammed bin Salman's ambitious plans to transform and diversify the Saudi economy and reduce its reliance on oil.
The Houthis say they have been retaliating for the kingdom's backing of Yemeni government forces in the Yemen war that restarted last month.
The Saudi-led coalition said it had intercepted a ballistic missile fired by the Houthis towards Riyadh on Wednesday, and several loud booms were heard in the Saudi capital.
Saudi authorities earlier issued an alert for a possible aerial threat in Riyadh on Wednesday before the warning was lifted, a witness said. It was not immediately clear what caused the booms and there was no immediate comment from the authorities on their source.
The Saudi government media office did not immediately respond to a request for comment about the cause of the booms.
In their statement on Wednesday, the Houthis said they had launched ballistic missiles, cruise missiles and drones at the Saudi Aramco facilities in Dhahran, Riyadh airport and an Aramco refinery in Riyadh.
In a broad threat, they urged "international shipping companies", civilians and workers to evacuate Saudi airports and oil facilities.
The Dhahran complex hosts a major operations centre for Aramco, which oversees a vast network of onshore and offshore oil rigs, pipelines, refineries and export terminals.
Riyadh's international airport has come under attack four times, including Saturday's attack, which was the deadliest in Saudi Arabia in a decade.
Authorities have closed the airport until 17 October, and airlines have cancelled flights to Saudi Arabia.
Fearing the rise of Iranian influence and the prospect of chaos on its borders, Saudi Arabia intervened in Yemen's civil war in support of the government in 2015 after the Houthis seized the capital, Sanaa.
The UN brokered a 2022 truce between the warring sides in Yemen that kept a fragile peace until this year.
Saudi Arabia resumed its military campaign in Yemen in support of the internationally recognised government in a bid to reverse the Houthis' sudden gains last month, when they swept down the Red Sea coast to the critical Bab el-Mandeb Strait.
The Red Cross said on Wednesday that hospitals across Yemen were struggling to cope with a sharp rise in war casualties as fighting intensified along multiple front lines.
The UN World Food Programme warned that life-saving assistance had been cut off to the government-held city of Taiz, which was encircled by Houthi fighters earlier this month.
"WFP and its partners cannot access more than 600,000 people in Taiz who depend on humanitarian assistance, including more than 200,000 women and children," WFP said in a statement.