When Countries Go to War: The Big Announcement!

A declaration of war is a formal, legal, and political act by which one sovereign state announces the existence of a state of war with another. This performative speech act, or the signing of a formal document, by an authorized party of a national government is intended to officially create a legal status of war between nations. Historically, such declarations were crucial for several reasons: they signaled the breakdown of diplomacy, informed citizens and the international community of the impending conflict, and triggered specific legal obligations and rights under both domestic and international law, such as the treatment of prisoners of war and the legality of blockades.

The competence to declare war has varied across different forms of government, often resting with the head of state or sovereign, underscoring the gravity of the decision.

The international community recognized the need for a more regulated approach to the commencement of hostilities. The Hague Convention (III) of 1907 concerning the Opening of Hostilities was a significant step in codifying the official international protocol. It stipulated that the existence of a state of war must be recognized by the other party and must be the subject of a written notification, which might take the form of a declaration of war, possibly conditional, preceded by a statement of reasons.

Prior to this, while declarations were common, there were also less formal methods, such as the issuance of letters of marque and reprisal, which authorized privateers to engage in hostilities, blurring the lines between state-sanctioned warfare and privateering.

The landscape of international law dramatically shifted after World War II with the establishment of the United Nations. The UN Charter, particularly Article 2(4), prohibits the threat or use of force against the territorial integrity or political independence of any state. This fundamental principle has rendered formal declarations of war largely obsolete in international relations.

While declarations may retain relevance within the domestic legal frameworks of belligerent or neutral nations, their utility as a trigger for international legal consequences has diminished. Instead, the UN Security Council, under Chapter VII of the Charter, can authorize collective action to maintain or enforce international peace and security, providing an alternative mechanism for addressing threats.

Despite the general prohibition on the use of force, Article 51 of the UN Charter preserves the inherent right to individual or collective self-defense if an armed attack occurs against a state. This provision has become a primary legal justification for military action in the post-declaration era. Conflicts today are often initiated through armed attacks that trigger self-defense responses, or through interventions authorized by the UN Security Council, rather than through formal declarations.

This evolution reflects a global consensus that formal declarations of war are often perceived as markers of aggression and maximalist aims, and that states should seek to avoid such overt pronouncements.

Scholars debate the reasons behind the decline of formal declarations of war. Some argue that states deliberately evade the restrictions and obligations imposed by international humanitarian law, which governs conduct in war, by not formally declaring it. Others suggest that declarations have become politically costly, signaling an aggressive stance and potentially inviting international condemnation or intervention.

The rise of asymmetric warfare, proxy conflicts, and cyber warfare further complicates the notion of a formal declaration. While the traditional declaration of war may be a relic of the past, the legal and political questions surrounding the initiation and conduct of armed conflict remain central to international security.