The US State Department has ordered non-emergency government employees and their families to leave Saudi Arabia amid escalating attacks by Yemen’s Houthi group, the US Embassy said Friday.

In a security alert, the US Mission to Saudi Arabia said the departure order took effect on Oct. 23 due to safety risks.

The mission warned that Houthi attacks on civilian airports and critical infrastructure had caused casualties and major travel disruptions, adding that hostilities could escalate rapidly.

US government employees must obtain special authorization to use airports in Saudi Arabia following recent missile and drone attacks, the statement said.

The embassy said Riyadh’s King Khalid International Airport had partially reopened, while airports in Jeddah and Dammam remained operational with some delays and cancellations.

It also urged US citizens to exercise extreme caution when traveling by air and warned against photographing missile interceptions or attack sites, citing Saudi regulations.

The alert comes amid intensified Houthi attacks against Saudi Arabia.

On Thursday, the Saudi-led coalition announced that its air defenses had intercepted and destroyed two ballistic missiles launched by the Houthis toward Riyadh.

On Friday, the coalition reported intercepting a Houthi cruise missile targeting western Saudi Arabia, as well as a drone in the Riyadh region.

The Houthis have also claimed attacks on Saudi oil facilities and airports in recent days.

The Saudi-led coalition intervened in Yemen in March 2015 to support the internationally recognized government against the Houthis, who have controlled the capital Sanaa since September 2014. (AA)