alert

be on full/red alert

if soldiers are on full alert, they know that a situation is dangerous and are prepared to act immediately if necessary. The British flagship in the area went to battle stations and remained on full alert for twenty minutes.

See also: full, red

be put on full/red alert

be on full/red alert - if soldiers are on full alert, they know that a situation is dangerous and are prepared to act immediately if necessary. The army was put on red alert as the peace talks began to break down.

See also: full, red