Washington is getting ready to send some of its diplomats and their families home from American embassies across the Gulf, according to three US officials who spoke to Reuters on Wednesday.

The State Department is preparing what is known as an “ordered departure” — a mandatory drawdown of personnel and dependents. Two of the officials said the decision is driven by concern that fighting could flare up again, with the Iran-backed Houthis in Yemen named as the primary worry.

Saudi Arabia may see the most sweeping step. According to two of the officials, the order could extend to every staff member and family at the US Mission there.

Earlier Wednesday, the US Embassy in Riyadh put out a security alert cautioning that the Houthis may launch more attacks on the kingdom. The warning follows a string of recent deadly strikes, some of which hit the area around Riyadh’s airport.

The State Department has not yet formally announced the order.