someone who fights (or is fighting)

characteristic of an enemy or one eager to fight; "aggressive acts against another country"; "a belligerent tone"

engaged in war; "belligerent (or warring) nations"; "a fighting war"

Inclined or eager to fight; hostile or aggressive.

group or nation which is engaged in a war or military conflict

In wartime, a nation at war.

A belligerent is an individual, group, country or other entity which acts in an aggressive or hostile manner, such as engaging in combat.