Defense condition one

From Memory Alpha, the free Star Trek reference

Defense condition one is an alert signal aboard Klingon starships announced during the preparation for battle, equivalent to a red alert aboard Federation starships.

General Martok called for the IKS Ch'Tang to set defense condition one prior to the ship's arrival and attack on the Dominion base on Trelka V. (DS9: "Once More Unto the Breach")

This term is a reference to the US military system of alert, known in shorthand as "DEFCON".