RIYADH/SANAA – The Saudi-led coalition in Yemen has vowed to respond firmly to a Houthi attack on a passenger terminal at King Khalid International Airport in Riyadh on Saturday that killed 12 people and injured 309 others.

Coalition spokesperson Turki Al-Malki said early Sunday on social media platform X that the coalition's Joint Forces Command would respond firmly to what he described as a "terrorist attack" in accordance with international humanitarian law.

In separate posts on Sunday, Al-Malki said the Saudi-led coalition had intercepted and destroyed a ballistic missile and a drone launched by the Houthi group toward Saudi Arabia.

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The fatalities in the airport attack included four Saudi citizens and eight foreign residents -- two Bangladeshis and one each from the United States, Egypt, Jordan, Syria, Palestine and Sudan, according to the Saudi aviation authority.

The authority said the injured were receiving treatment at several hospitals, with some in serious condition, and that airport operations had been temporarily suspended.

Houthis renew warning over Saudi airports, airspace

Yemen's Houthi group on Sunday renewed its warning to airlines, aviation workers and travelers against using airports and airspace in Saudi Arabia amid escalating cross-border hostilities.

Houthi military spokesperson Yahya Sarea said in a statement posted on social media platform X that Saudi airports and airspace, except for the airports in the Islamic holy cities of Mecca and Medina, remained "exposed to targeting" and constituted an area of operations for the group's forces.

Sarea urged airlines, aviation personnel and travelers to take the warnings seriously, saying the Houthis would maintain their declared formula of "airport for airport, blockade for blockade and escalation for escalation" until the group achieves its objectives.

The attack at King Khalid International Airport came as the Houthi group and Saudi Arabia continued exchanging strikes on major airports and other facilities.

Three people were killed and 36 others injured in two separate attacks targeting Abha International Airport in southwestern Saudi Arabia and King Khalid International Airport on Tuesday and Wednesday, respectively. On Thursday, three Saudi citizens, including a pilot, were killed and several others of other nationalities were injured in two Houthi attacks targeting King Khalid International Airport.

Houthi-run al-Masirah TV reported earlier on Saturday that Saudi Arabia launched a new wave of air and missile strikes across Houthi-held areas in Yemen, targeting Sanaa International Airport in the Houthi-held capital, areas near the strategic Bab al-Mandab Strait and several northern provinces.

ALSO READ: 3 Saudis killed in attacks targeting Riyadh's King Khalid Int'l Airport

Also on Saturday, Yemen's government forces said that more than 1,150 Houthi fighters had been "neutralized" and over 180 military and logistical vehicles destroyed or damaged in over 1,900 strikes across multiple fronts in Yemen over the preceding 24 hours.

The figures could not be independently verified.

Yemen has been mired in conflict since late 2014, when the Houthis seized the capital Sanaa and much of the country's north. A Saudi-led coalition intervened in 2015 in support of the internationally recognized Yemeni government, now based in the southern port city of Aden. The renewed fighting marks a major escalation after a UN-brokered truce in 2022 largely halted major hostilities.

US President Donald Trump said Saturday that the United States "may" join Saudi Arabia in striking the Houthi group.

"We just found out about the recent attack. So we'll make a decision. We move very quickly," he told reporters on the South Lawn of the White House.

READ MORE: Yemen's Houthis claim ballistic missile attack on Riyadh airport

UN Secretary-General Antonio Guterres on Sunday strongly condemned Saturday's Houthi attack on King Khalid International Airport in Riyadh.

"Attacks on civilians and civilian infrastructure are a violation of international law. These attacks must cease immediately," he wrote on X. 

UN Special Envoy for Yemen Hans Grundberg on Sunday condemned continuing Houthi attacks on civilian infrastructure in Saudi Arabia, warning that the escalation threatens regional security and further complicates peace efforts in Yemen.

"These attacks represent a grave escalation," Grundberg said, adding that such actions "pose a serious threat to regional security, perpetuate cycles of violence and complicate even more peace efforts for Yemen."