The Houthis renew their threats against Saudi airports, the day after the deadly attack in Riyadh

Yemen's pro-Iranian Houthis renewed their threat on Sunday to strike Saudi airports and airspace, a day after an attack on Riyadh airport that killed 12 people, the deadliest in the kingdom in ten years.

The scale of the attacks targeting Riyadh in recent days is unprecedented since the start in 2014 of the war in Yemen between the Houthis and government forces, who received military support from a Saudi-led coalition a year later.

Without claiming responsibility for Saturday's strike, the Houthis renewed on Sunday their warning to travelers, employees and airlines not to use Saudi airspace and airports, "with the exception" of those in the holy cities of Mecca and Medina.

"They are exposed to strikes," warned Yahya Saree, their military spokesman, on X.

Pro-Iranian fighters had already claimed responsibility on Wednesday and Thursday for attacks against Riyadh airport, which killed a total of six people.

The military coalition led by the kingdom blamed them for Saturday's strike, denouncing it as "a war crime" to which it would respond "firmly." A diplomatic source also attributed it to a Houthi missile.

This is the deadliest attack in the kingdom since a suicide bombing by the jihadist group Islamic State (IS) that killed 15 people in August 2015.

International condemnations of the strike on civilian infrastructure poured in. "What happened (...) is not acceptable," Donald Trump reacted on Saturday, indicating that he would examine possible American participation in military operations against the Houthis, and would speak with Crown Prince Mohammed bin Salman, the de facto ruler of the kingdom.

The United States had not previously responded to several Saudi requests for support.

- The airport is still at a standstill -

Saudi authorities have reported 12 people killed and 309 injured at King Khalid International Airport, but the toll could be higher, a Western diplomat based in Riyadh told AFP.

"Four Saudi nationals, two Bangladeshis, an American, an Egyptian, an Argentinian, a Syrian, a Palestinian and a Sudanese" are among the dead, according to authorities.

"I saw injured people. Everyone was running," a passenger, who was waiting for a flight near the affected terminal, told AFP.

On Saturday evening, the coalition also reported that a projectile had fallen near Dammam airport (east).

The airport in the Saudi capital will remain closed on Sunday, two aviation industry sources confirmed to AFP.

"Operations are suspended until further notice," said one of the sources, who added that the radar and communication equipment had been damaged, and the condition of the runways had to be assessed.

A French resident in Riyadh, whose flight was cancelled, told AFP on Sunday that she would drive to Doha, Qatar, to catch her flight.

The Saudi embassy in Kuwait will charter buses on Monday to repatriate Saudi nationals stranded in the small emirate.

Several foreign embassies have advised their employees to avoid Riyadh airport for a week, a Western diplomat told AFP.

And the US embassy has extended to the airports of Dammam and Jeddah access restrictions already imposed on its staff for the Riyadh airport.

The kingdom is set to host a series of major international conferences this month, attracting foreign leaders and business figures.

Several companies in Riyadh's business center put their staff on remote work on Sunday, according to numerous employees, and schools in the capital switched to remote learning for the week.

- "Dangerous escalation" -

The UN, Paris, London, Berlin, Doha, Amman, Baghdad and Islamabad condemned the airport attack, which was described as a "dangerous escalation" by the President of the European Commission, Ursula von der Leyen.

Despite diplomatic differences, particularly in Yemen, the United Arab Emirates expressed their solidarity with the kingdom and their "support for all measures aimed at preserving" its security.

On the ground in Yemen, hostilities continue after the lightning offensive launched in September by the Houthis who took control of the strategic Bab el-Mandeb strait on the Red Sea, triggering a government counter-offensive.

The Houthis reported on Sunday two Saudi strikes on the governorate of the capital, Sanaa, which is held by the movement.

Military sources from the government camp told AFP on Saturday that Yemeni forces had advanced around the strait, but failed to secure it.

A Houthi official asserted that the movement still held Mayyoun Island, at the heart of the maritime passage which has gained importance since Tehran restricted navigation in the Strait of Hormuz, on the other side of the Arabian Peninsula.