Iran-backed Houthi rebels launched a huge barrage of drones at Saudi Arabia on Sunday. Air defences in the kingdom knocked out 12 armed drones. Although the Yemeni rebels have been launching near-daily attacks against the kingdom with missiles and armed drones, on Saturday the Houthis fired eight drones and then that increased on Sunday to 10 more. The increase marks a significant escalation in such attacks. The Saudi-led coalition supporting Yemen's government did not state the targets of the attacks other than to say they targeted “civilian sites”. "Civilians and civilian objects in Saudi Arabia are a red line," The coalition said according to state-owned <em>Al Arabiya</em> news. "We will hold accountable terrorist leaders who try to target civilians and civilian objects." The coalition hit areas around Sanaa later on Sunday and several other provinces and added that the operation was carried out in accordance with international law, state-owned Al Arabiya media reported. Reports also said that at least 70 Houthi fighters had been killed in the south-west city of Taiz on Sunday, although it is unclear if this was part of the same operation. The US consulate in the Saudi Red Sea city of Jeddah issued an advisory, citing reports of suspected attacks and explosions on Sunday near the city and the southern town of Khamis Mushait. Social media users, using the hashtag "Jeddah Now" on Twitter, reported hearing explosions in Jeddah on Sunday morning. The UAE on Sunday condemned the "systematic terrorist attacks" by the Houthis.<br/> The Foreign Ministry said the attacks showed the group's disregard for the international community and international laws and norms. The attacks, that have wounded civilians and hit non-military buildings, have been condemned by the international community and the US has promised to assist Saudi Arabia to bolster air defences. Houthi attacks on Saudi Arabia have increased in recent days as rebels and pro-government forces, backed by the coalition, engage in heavy fighting in the northern Yemeni province of Marib. “The on-ground reality and the victories of the Yemeni army and the tribes in Marib illustrate the pace of escalation by the Houthis,” the coalition said, adding it will continue to take all measures to protect civilians. Yemeni government military sources said on Saturday that at least 90 combatants from both sides had been killed in Marib in the previous 24 hours. The coalition intercepted seven Houthi drones launched towards southern Saudi Arabia on Saturday, seven aimed at the city of Khamis Mushait and one at the port city Jazan. On Friday, the Saudi Air Defence said it intercepted and destroyed six bomb-laden Houthi drones launched towards Khamis Mushait. A 10-year-old child and an adult civilian were injured by falling debris from those attacks, according to the civil defence authority in Asir province. The Saudi-led coalition intervened in Yemen in 2015 at the request of the internationally recognised government of President Abdrabu Mansur Hadi after the Houthi rebels took over the capital, imprisoned ministers and officials and took power.