He said embassy staff were still in a heightened state of alert but there were no specific threats against any staff members.

他说尽管没有针对使馆人员的具体威胁，他们仍处在高度戒备状态。

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And this is obviously a cause for concern and requires a heightened state of alert.

WHITEHOUSE: The Necessity of Science

The CTC, fearful of another strike around the July 4 holiday, is "on a heightened state of alert, " says Bernazzani.

CNN: At the crossroads of terror

U.S. forces -- reacting to a heightened state of alert for terror attacks -- are braced for guerrilla assaults during the holiday season.

CNN: Military investigates hostile fire in 'green zone'