warning shot

warning shot (plural warning shots)

1. Used other than figuratively or idiomatically: A shot fired as a warning..
2. (by extension, figuratively) An action intended to act as a warning.

   Synonyms: shot across the bow, shot across the bows

   • 2005, J. H. Snider, Speak Softly and Carry a Big Stick: How Local TV Broadcasters Exert Political Power, →ISBN, page 487:

     I believe that most members of Congress interpreted these ads as a warning shot rather than an effective grass roots mobilization tool.