The authority to initiate hostilities against another country resides at the national level. This power, a cornerstone of sovereignty, allows a nation to protect its interests, defend its territory, and uphold international obligations. For example, in the United States, the Constitution grants Congress the explicit power to declare war.
Centralizing the decision to engage in armed conflict ensures a unified and considered response to external threats. It necessitates deliberation among elected representatives, fostering a broader perspective than might exist within a single executive office. Historically, this safeguard has been implemented to prevent rash or unilateral actions that could have profound and lasting consequences for the nation and its citizens.