The US State Department warned Americans on Saturday of possible flight cancellations and airspace closures as fighting between Saudi Arabia and Yemen’s Houthis threatened to escalate rapidly. It urged Americans outside the Middle East to reconsider travel to or through the region, citing Houthi hostilities against Saudi Arabia, including civilian airports.

US security alerts covered Israel, Iraq, Lebanon, Oman, Bahrain, Kuwait, Jordan, Saudi Arabia, Qatar and Iran. Americans in the region were urged to exercise heightened vigilance and monitor airport and airline operations. The department also warned that Iran and groups supporting it could target US interests worldwide, including businesses and other institutions, noting that US diplomatic facilities outside the Middle East had been targeted.

Earlier Saturday, a fire broke out at an Aramco fuel tank near Riyadh’s King Khalid International Airport, where flights were canceled and delayed. The Houthis claimed missile and drone attacks on sites in Riyadh and Aramco facilities in Yanbu, without specifically naming the airport. The Saudi-led coalition said it intercepted and destroyed a Houthi ballistic missile headed toward Riyadh and thwarted attacks on other Saudi cities.