declare war on

Idioms  

1. Also, declare war against. Announce one's intent to suppress or eradicate something or someone. For example, The police have declared war on drug dealing in the neighborhood, or Several gangs have declared war against each other. This usage transfers the literal sense of the term, “to state formally one's intention to carry on hostilities against another power,” to a somewhat smaller scale.

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Example Sentences

See Examples For:

declare war on

The attack on the base, as well as similar attacks in the Philippines and Guam, spurred the United States to declare war on Japan.

From Salon ● Mar. 19, 2026

Prof Kivutha Kibwana, a law scholar and a former county governor, urged dialogue in his post on X: "The most dangerous thing for a government to do is to declare war on its youth."

From BBC ● Jun. 19, 2024

The attacks prompted Mr. Netanyahu to declare war on the militant group.

From Washington Times ● Oct. 7, 2023

But at the same time, the country cannot move forward if Americans declare war on each other and assume communication is impossible.

From Los Angeles Times ● Feb. 7, 2022

Britain and France had promised to protect Poland—they had no choice but to declare war on Germany.

From "Bomb" by Steve Sheinkin