The airport in Saudi Arabia's capital, Riyadh, was attacked again Saturday and evacuated, two regional officials said, just days after three Saudi citizens, including a pilot, were killed as the kingdom faces an extraordinary series of assaults in a new front in the Iran war.

President Donald Trump told reporters he was evaluating whether the United States should join Saudi strikes against the Iran-backed Houthi rebels in neighboring Yemen, who have claimed this week's attacks on King Khalid International Airport as well as other Saudi airports, military facilities and oil infrastructure.

"We may. We're going to look at it," Trump said. "We just found out about the recent attack. So we'll make a decision. We move very quickly."

In the latest attack, a missile struck a complex housing terminals 3 and 4, which handle domestic flights at the Riyadh airport, and many people were wounded, one of the regional officials said. The officials spoke on condition of anonymity because they were not authorized to speak to the media. Ambulances were seen rushing to the scene.

The surge in attacks has come in the week since a Saudi-led coalition launched a major military offensive against the Houthis. There was no immediate Houthi statement Saturday. The open questions from here: whether the U.S. formally joins the strikes, the final assessment of Saturday's casualties and damage, and whether the Houthis claim the latest attack.

Saudi civil aviation authorities said operations at the airport had been suspended and that the number of wounded and the extent of the damage were being assessed. The airport had a heavy police presence, with all entrances blocked, and lights around the complex were dimmed. Flights were diverted elsewhere, according to the Flightradar24 tracker, and countries including the United States, Britain, Germany, Australia and Canada warned citizens to avoid the airport.

The attacks on airports, military facilities and oil infrastructure in Saudi Arabia, the world's top oil exporter, have rattled markets and the region.

Fighting in Yemen between the Houthis and Saudi-backed Yemeni government forces has escalated, with the Saudi-led coalition providing air support for government forces in an attempt to reverse recent Houthi gains along the Red Sea. Those gains have given the rebels better surveillance of shipping on a corridor that serves as a crucial alternative to the Strait of Hormuz, where Iran has been attacking ships.

Though the Houthis have told the AP and others they are targeting only Saudi shipping as part of a blockade in retaliation for one imposed on them, concerns about wider attacks persist. The rebels previously attacked other ships after the war in Gaza began, calling it an act of solidarity with Palestinians; a U.S. bombing campaign ended that.

Saudi Arabia is running low on missile interceptors and has asked France, Britain, Pakistan and Egypt to deploy air defense support to the region, regional officials told the AP last month, with one noting that the United States has seen its own stock dwindle during the war with Iran. Officials said U.S. assistance has included intelligence sharing, target identification and planning for the latest offensive. That squeeze on interceptor stocks on both sides adds a resource dimension to Trump's decision on whether to join the strikes.

The Saudi and Omani foreign ministers spoke by phone about the importance of "supporting diplomatic solutions to de-escalate tensions" in the region, the kingdom said Saturday. Oman, which lies across the Strait of Hormuz from Iran, has played a mediator role at times in the region.

Meanwhile, Saudi authorities warned the public this week that "filming, publishing or sharing information related to countering missiles and drones and their impact sites exposes you to legal liability."

Also this week, the Houthis warned global airlines "for the last time" about the potential consequences of operating in Saudi airspace, which they described as a theater for their military operations.

At least 225 flights at the Riyadh airport had been canceled over the past 24 hours, according to flight-tracking site FlightAware. Air India, FlyDubai, Lufthansa Group and Pakistan International Airlines have been among the airlines suspending flights to and from Riyadh and other Saudi airports for the next few days.

The European Union Aviation Safety Agency has expanded its guidance on Saudi airspace, noting the Houthis' ability to strike targets deeper inside the kingdom, including Riyadh, and a "greater focus on aviation infrastructure." The agency said the missile and drone attacks and interception efforts "create an increased risk of misidentification of civil aircraft." Read together, the Houthi warning, the airline suspensions and the regulator's guidance show how the conflict's risks now extend beyond Red Sea shipping to commercial aviation itself.

In Thursday's attack, Saudi Arabia's national carrier said one of its aircraft was damaged while it was on the ground, with no passengers on board.

This story was originally featured on Fortune.com.