They told all US citizens to defer any non-essential travel to the country. The US embassy in Riyadh had earlier warned its nationals of possible attacks during the holy Muslim month of Ramzan
"There is credible information that terrorists have targeted Western aviation interests in Saudi Arabia. The Department of State warns US citizens to defer nonessential travel to Saudi Arabia. Americans are reminded of the potential for further terrorist actions against US citizens abroad, including in the Persian Gulf region," it said.
The US warning follows a similar advisory issued by the Foreign Office to British citizens last week.