The State Department is ordering some diplomats and the families of U.S. government employees to leave Saudi Arabia following a series of deadly attacks in the country by Yemen’s Iran-backed Houthi rebels and rising fears of an escalation in hostilities.

The department said Wednesday it had ordered the departure of non-essential staff at the U.S. Embassy in Riyadh and its satellite consulates. The embassy had been badly damaged at the start of the Iran war and had been operating with only a skeleton staff for months, although some diplomats had returned in recent months.

In a new travel alert, the department said, "Iranian-supported Houthis have engaged in hostilities against Saudi Arabia, including attacks on civilian airports and other critical infrastructure resulting in civilian casualties and severe travel disruptions. The hostilities have the potential to escalate rapidly beyond that immediate area.”

A series of previous alerts for Saudi Arabia issued over the past several days have used almost identical language and noted that U.S. government personnel need special permission to use any Saudi airport. The Houthis have routinely targeted Riyadh’s King Khalid International Airport, and it had been closed since Oct. 10 following a severe attack.

But earlier Wednesday, aircraft from a limited number of Saudi airlines took off and landed at the airport, two days after Saudi aviation authorities notified airlines that they could resume operations with prior permission.

Still, major carriers like Lufthansa and Air France have canceled flights to Riyadh through mid-November. Saudi airlines, including Saudia and FlyNas, were among those operating flights Wednesday.

The Houthis have acknowledged attacking the airport, claiming without evidence that Saudi Arabia provided military equipment to government forces through the facility.

Although the ordered departure applies only to Saudi Arabia, U.S. embassies in other Gulf countries will see temporary staffing changes, the department said. Those embassies are already under “restricted operations” that limit the number of personnel working there.

Meanwhile, tensions grew as Saudi Arabia’s Energy Ministry said debris from an intercepted drone killed two people and injured two others at an Aramco-operated oil field in the country’s southeast.

The Saudi-led coalition fighting the Houthis also said the group had fired five drones toward Saudi Arabia early Wednesday. The coalition said the drones were intercepted and destroyed over the holy city of Madinah and the Eastern Region.

The attempted attack was the latest on Saudi Arabia since the resurgence of fighting with the Houthis in mid-July.