A warning shot is a military term describing harmless artillery shot or gunshot intended to call attention and demand some action of compliance. It is recognised as signalling intended confrontations on land, sea and air.
As an analogy, "warning shot" can be said of any action of declaration, especially a demonstration of power, intended or perceived as a last warning before hostile measures.
Famous quotes containing the words warning and/or shot:
“An overturned cart is a warning to oncoming drivers.”
—Chinese proverb.
“In health of mind and body, men should see with their own eyes, hear and speak without trumpets, walk on their feet, not on wheels, and work and war with their arms, not with engine-beams, nor rifles warranted to kill twenty men at a shot before you can see them.”
—John Ruskin (1819–1900)