shot across the bow

Etymology
From the naval tactic of firing a warning shot across the bow or front portion of a ship in order to force it to stop or alter its course.

Noun

 * 1)  A warning that negative consequences will be faced if something is carried out or allowed to continue.

Translations

 * Finnish: varoituslaukaus
 * German: Schuss vor den Bug
 * Norwegian:
 * Bokmål: ,
 * Nynorsk:
 * Russian: предупреди́тельный вы́стрел