Instrumental aggression is defined by its purpose: to achieve objectives that are not inherently aggressive. This contrasts with hostile aggression, which directly aims to inflict harm. Instrumental aggression is strategic and calculated, focused on reaching a specific, often unrelated, non-aggressive outcome. The driving force is the attainment of an objective, not the infliction of harm.
Therefore, the primary objective of instrumental aggression is best described as "Attaining non-aggressive goals". This differentiates it from actions motivated by emotions like jealousy or the desire to cause physical or psychological distress.