In which scenario would a declared hostile act be unnecessary before military engagement?

In the context of military engagement, confronting a declared hostile force inherently implies that the adversary has already identified themselves as a threat through their actions or declarations. Therefore, the necessity for a further declaration or assessment of a hostile act is bypassed because the nature of the interaction is defined by inherent hostility.

When military personnel engage with a declared hostile force, they operate under the understanding that the enemy's intentions and actions are aggressive or dangerous, which allows for immediate engagement based on established rules of engagement. This situation contrasts sharply with scenarios involving civilian interactions, peaceful negotiations, or assessments of compliance with international law, where a clear determination of hostility is critical before any military action is contemplated.