casus belli

Definition

Noun:
- An event or action that is used to justify a declaration of war: A specific incident or act that a nation or political entity cites as the direct, formal reason for initiating armed conflict.

Usage

The word "casus belli" is a formal, diplomatic, and historical term. It is used in political science, international relations, and historical analysis to discuss the stated reasons for war. It often implies a distinction between the publicly declared cause and other underlying motives.
It is typically used in the singular form. The plural is "casus belli" (same spelling) or the Anglicized "casus bellis."
In a sentence, it often follows verbs like "serve as," "provide," "become," or "cite."

Examples

The assassination of the archduke served as the casus belli for the First World War.
The government claimed the border incursion was a clear casus belli.
Historians debate whether the incident was a genuine casus belli or merely a pretext for a planned invasion.

Advanced Usage

"A casus belli": Used to describe an event that meets the threshold for justifying war under international law or a nation's own political doctrines.
- The treaty violation was considered a sufficient casus belli by the council.
The concept is central to the "Just War" theory (), which examines the justifications for going to war.

Variants and Related Words

Pretext (n): A reason given to conceal the true reason; often used when the is believed to be false or exaggerated.
- The attack was merely a pretext for a larger conflict.
Jus ad bellum (n): The body of law, ethics, and norms concerning the justification for resorting to war.
Provocation (n): An action or speech that makes someone angry, especially deliberately; can be a type of .

Synonyms

Cause for war: The direct reason for starting a war.
Justification for war: The grounds given for declaring war.
Casus foederis (n): The case or event that triggers obligations under a treaty of alliance, which may lead to a for an allied nation.

Notes on Meaning

The term is directly borrowed from Latin, meaning "case for war."
It specifically refers to the cause or trigger, as opposed to long-term, underlying causes (e.g., economic rivalry, ideological differences), which are often called "underlying causes" or "root causes."

Noun