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:
“By day thy warning ringing bell to sound its notes,
By night thy silent signal lamps to swing.”
—Walt Whitman (1819–1892)
“By the rude bridge that arched the flood,
Their flag to April’s breeze unfurled,
Here once the embattled farmers stood
And fired the shot heard round the world.”
—Ralph Waldo Emerson (1803–1882)