The US Department of State warned that military conflict could expand in a short period, saying that tensions had made the security environment in the Middle East more complex. The department said an unexpected escalation could occur in the region.
US citizens living in the region were urged to remain alert to flight cancellations, airspace closures and possible disruptions to transportation. US citizens outside the Middle East were also called on to seriously reconsider travel plans to or through the region.
Warning of threats to US facilities
The US Department of State said US diplomatic compounds, including some facilities outside the Middle East, had previously been targeted. The department also warned that Iran and groups it supports could target other US interests abroad, locations linked to the United States, and American companies and institutions around the world.
The statement also urged US citizens in the Middle East to monitor the operational status of airports and airlines.
Missile and attack attempts in Saudi Arabia
The US warning came after new military activities by Yemen's Houthis targeting Saudi Arabia. The Saudi-led coalition said it had intercepted and destroyed a ballistic missile launched toward Riyadh.
The coalition announced that attempts targeting the areas of Bisha, Taif, Farasan and Yanbu had also been thwarted. Saudi Arabia's Civil Defense units activated early-warning sirens in Riyadh, Al-Kharj and Farasan, then announced that the danger had ended.
Background to the Yemen conflict
On July 20, the Houthis announced that they were imposing a maritime blockade on Saudi Arabia. The group later said that Saudi ships and locations had been targeted with missiles and unmanned aerial vehicles, describing the actions as a response to what it claimed was a Saudi naval and air blockade of areas under its control in Yemen.
Saudi Arabia has led a coalition supporting Yemen's internationally recognized government since March 2015. The Houthis have controlled the capital, Sanaa, as well as various parts of Yemen since September 2014.