As Saudi Arabia reckons with the deadliest attack on its soil in more than a decade, questions swirl over how Riyadh will respond as Yemen’s Iran-allied Houthis continue to wreak havoc on the kingdom.

The kingdom launched a major offensive last week to support Yemeni government forces fighting the Houthis, but the rebels have so far held their ground.

Instead, they have escalated their campaign against the kingdom, culminating in Saturday’s missile attack on Riyadh’s King Khalid International Airport that killed at least 12 people.

Drawing from Iran’s playbook in its conflict with the United States, the Houthis are vowing a painful escalation, targeting critical infrastructure in Saudi Arabia and imposing a global economic cost.

The Houthis have longstanding grievances against Saudi Arabia over Riyadh’s decade-long war against the group, which triggered the world’s worst humanitarian crisis. The recent Houthi escalation, however, is increasingly seen as an extension of Iran’s conflict with Washington.

After eleven years of trying to contain the Houthi advance militarily and through talks, Saudi Crown Prince Mohammed bin Salman and his brother, Defense Minister Khaled bin Salman, face limited options. Across the border, the rebels have grown more powerful, consolidating control over major cities and pushing to seize others, such as the densely populated Taiz.

“This threat has to be dealt with once and for all,” Ali Shihabi, an author and commentator on Saudi politics told CNN. “A lot will depend on the performance of the Yemeni government troops on the ground and Saudi is helping them extensively with air power.”

So far, Saudi Arabia has largely confined its role to providing air cover for the anti-Houthi Yemeni coalition, stopping short of any major deployment of its own troops on the ground. Whether that restraint will hold after Saturday’s strike on Riyadh remains an open question.

Sending large numbers of Saudi troops into Yemen would plunge the kingdom into a an expensive and grinding ground war across rugged terrain and undercut the image Crown Prince Mohammed bin Salman is carefully cultivating of a stable, investment-friendly kingdom and global tourism hub.

Better missile capability

Barely two decades ago, the Houthis were little more than a small religious revivalist movement. With Iranian backing, they have since grown into a formidable fighting force in possession of ballistic missiles and capable of striking as far away as Tel Aviv.

“They’ve developed their warfare,” a southern Yemeni official who fought the Houthis for years told CNN. “They’ve gotten more sophisticated in their attacks, they’re persistent and they’ve enhanced their intelligence.”

Yemen’s government alleges that Houthi rebels have worked with Iranian Revolutionary Guard experts to modify missiles into more effective weapons.

The new missiles fly faster and use a thermal-tracking system to home in on any heat source, Majed al-Nazili, spokesperson for the Yemen’s armed forces, said. It remains unclear whether such missiles were used during Saturday’s attack on Riyadh airport.

The Houthis’ pursuit of more sophisticated weapons may now be extending into artificial intelligence.

AI company Anthropic said a group based in northern Yemen used its Claude AI tools to help develop guidance software for rockets and missiles – the systems that steer and stabilize the weapons in flight. The report did not identify those involved, but their location in Houthi-controlled northern Yemen suggests a possible link to the rebels.

Seeking international support

Saudi Arabia has sought support from partners across the world to counter the group. France, Britain and Pakistan have committed support, while other allies like Turkey are considering sending help.

Prince Mohammed has also reportedly turned to Syria for help. Its president, Ahmed al-Sharaa, had led armed factions that successfully drove Iranian-backed groups from Syria after nearly a decade of civil war.

Yet Riyadh’s biggest ally, the US, has not supported air strikes on the Houthis, instead sending more than 100 military advisers to provide intelligence under a newly formed joint command.

Last year Washington reached a ceasefire with the Iran-backed group that reopened the Bab al-Mandeb Strait, the maritime chokepoint through which global trade flows between Asia and Europe, to US vessels. Prince Mohammed spoke twice with Trump last month, urging him to strike the Houthis, sources told CNN at the time, but the president declined to intervene.

“Clearly, direct US involvement via air power would help because US aircraft can respond to US satellite intelligence more rapidly,” Shihabi said. “Saudi aircraft… are one stop removed from that loop so US involvement would be helpful.”

Saudi Arabia, one of the largest countries in the Middle East, remains vulnerable despite procuring some of the most advanced US air defenses. Its infrastructure, which carries rich resources across vast desert terrain, leaves it an easy target for the cheaper one-way drones developed by the Houthis.

Among those killed in the Houthi attack on the Riyadh airport was an American citizen, the Saudi civil aviation body said Sunday – an attack that might draw Trump further into the war.

“The Saudis are good fighters,” Trump told reporters following the attack. “But I think the attack was a terrible thing.”

Asked whether the US will join strikes on the Houthis, the US president said: “We may”