'Swift response': Houthis threaten US interests across region if Washington enters Yemen war

• Trump says Washington considering joining Saudi strikes against the Houthis.
• Etihad, Gulf Air cancel flights to Riyadh, while Delta delays planned service.
• UN human rights chief condemns attacks, urges both sides to de-escalate.

A Houthi official on Monday warned the United States it would face a "painful response" if it entered the war in Yemen, where Saudi Arabia has reportedly sought Washington's help in countering repeated attacks by the group.

Yemen's civil war, in which a Saudi-led military coalition supports the government against the Iran-backed Houthis, reignited in July, months into a wider regional conflict that has roiled energy markets and plunged the Middle East into crisis.

The Houthis quickly began targeting Saudi oil facilities, tankers and transport hubs, including a series of deadly strikes on Riyadh's airport, shaking the world's top oil exporter.

Explosions were heard over the Saudi capital again on Monday night. The Saudi-led coalition said it had intercepted a Houthi missile, while the group said it had again targeted the airport.

Later, the coalition announced it had intercepted two ballistic missiles in the south of the kingdom, near the border with Yemen.

In a statement posted on X, the coalition said it had "intercepted and destroyed two ballistic missiles launched by the terrorist Houthi militia towards Khamis Mushait", a city where a Saudi military base has previously come under attack.

Following a strike on Riyadh airport on Saturday that killed 13 people, US President Donald Trump said he was considering joining Saudi strikes against the Houthis, after reportedly rebuffing previous requests for assistance from the kingdom.

"The Houthis are misbehaving very badly. They're misbehaving very badly. No good," Trump said on Monday.

"If the US becomes involved in the aggression against Yemen, we will not deliberate over the decision to respond; rather, there will be a swift and painful response targeting the US and all its interests in the region," Houthi political bureau member Mohammed Al Bukhaiti told AFP in an interview.

He also warned, "all employees and workers at Saudi oil facilities and airports to stay away from these sites, as they have become legitimate targets".

Saturday's strike on King Khalid International Airport was the deadliest attack on Saudi soil in more than a decade and left hundreds wounded.

Trump described the attack as "not acceptable" and said he would speak to Saudi Arabia's de facto leader, Crown Prince Mohammed bin Salman. He told reporters that Washington was "going to look at" the possibility of joining Saudi strikes.

Operations remained suspended at the sprawling airport on the outskirts of Riyadh on Monday.

'Serious' response

Bukhaiti said the campaign against Saudi targets was intended to send a message to the crown prince "that he can no longer wage aggression against Yemen from a safe position".

Saudi Energy Minister Prince Abdulaziz bin Salman told a conference in Riyadh on Monday that recent events had "tested our infrastructure, our institutions, our people, and our resilience".

"The events of recent weeks are serious, our response must be equally serious," he said.

CCTV footage of Saturday's attack released by Saudi authorities showed Muslim pilgrims in religious attire waiting in departure lounges before a sudden blast tore through the building and brought down flaming debris.

The atmosphere in Riyadh remained tense on Monday, as state broadcaster Al Ekhbariya reported that the military coalition was responding to drone and missile threats.

In the evening, mobile phones received a loud government alert warning of a "hostile aerial threat", before the announcement of the interception.

The alert delayed the kick-off of a football match between Uzbekistan's Neftchi Fergana and Saudi team Al Nassr, which features Portuguese superstar Cristiano Ronaldo.

It was the first use of the phone alert system in Riyadh in weeks. No official explanation was given for the lack of alerts during attacks on the capital in recent days.

The Houthis also said they had targeted the Khamis Mushait base in southern Saudi Arabia with a drone.

Flights suspended

The US embassy in Saudi Arabia said US government employees must obtain its authorisation before using any airport in the kingdom. It also urged US citizens to "take extreme caution" if they chose to travel by air.

The mission said "American citizens have been detained for taking photos of recent events" in Saudi Arabia.

The UAE's national carrier, Etihad Airways, announced on Monday that it was cancelling all flights to and from Riyadh until the following week. It also suspended flights to Dammam and Jeddah.

Bahrain's national carrier, Gulf Air, said it was cancelling all Riyadh flights until Saturday.

US airline Delta announced that it would delay the launch of direct flights from Atlanta to Riyadh, which had been scheduled for October 23.

Despite heavy spending on military hardware, Houthi attacks on oil, military and transport facilities across the vast, mostly desert kingdom are putting Saudi defences under pressure.

Thomas Juneau, a security analyst at the University of Ottawa, said that despite some successes, "Saudi Arabia is so large that it's simply impossible for them to consistently defend themselves".

Riyadh has led an international coalition supporting Yemen's government militarily since 2015, including efforts to control Yemeni airspace and the airport in the Houthi-held capital, Sanaa.

Juneau said the Houthis now "want to do to Saudi Arabia what Saudi Arabia does to them".

Yemen's long-running civil war has created a deeply entrenched humanitarian crisis in the impoverished country.

UN human rights chief Volker Turk said he was "appalled by the repeated attacks" on Saudi Arabia, but urged both sides to de-escalate, warning that "continued fighting will only unleash further misery with no end in sight".