State Department officials said Thursday that they were taking action out of an "abundance of caution."
Spokeswoman Marie Harf cited information indicating a threat to U.S. facilities overseas and said some diplomatic facilities may stay closed for more than a day.
Other U.S. officials said the threat was in the Muslim world, where Sunday is a workday. American diplomatic missions in Europe, Latin America and many other places are closed on Sunday.
Those officials spoke on condition of anonymity because they weren't authorized to speak publicly about the matter.
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