US embassies in the Gulf and Egypt are calling for vigilance after a post on a jihadist website encouraged attacks on American and other international schools there, specifically teachers.
The warnings have been issued by missions in Egypt, Kuwait, Oman, Saudi Arabia and the United Arab Emirates.
While each of them said no specific threat had been identified in their respective countries, they urged Americans to be more careful about their security.
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The US embassy in Riyadh said the anonymous jihadist post specifically mentioned schools in Jeddah, Saudi Arabia and Maadi, an upmarket suburb of Cairo, saying the two cities have a "high concentration of potential targets".
A similar message was issued by the embassy in Cairo, which said it was "working with local schools identified with the United States or that have high concentrations of American teachers or students to review and enhance their security posture".
It also said "Americans residing in or visiting Egypt should remain vigilant regarding their personal security and alert to local security developments".
The other messages made similar observations.