Disrupting an adversary's communication through cyber means is primarily a function of which operation?

Disrupting an adversary's communication through cyber means falls primarily under the concept of Computer Network Attack. This operation involves the deliberate action taken to degrade, disrupt, or deny the operational capabilities of an adversary's information systems or networks. By targeting the communication systems of an enemy, a military force can create confusion, disrupt command and control, and ultimately hinder the enemy's ability to operate effectively.

Computer Network Attack encompasses a variety of strategies and tactics aimed at interfering with an adversary's electronic communications, which can be critical for their coordination and decision-making processes. This might include activities such as hacking into communication networks and altering or destroying data, thereby undermining their functionality and reliability.

In contrast, the other options—such as Computer Network Defense, Psychological Operations, and Information Assurance—focus on protecting one’s own systems, influencing perceptions and behavior without direct disruption, or ensuring that information systems are secure and reliable. While these are all vital components of modern military operations, they do not primarily focus on disrupting an adversary's communication in the manner described in the question.