Which of the following is NOT a category of COMSEC incidents?

The correct choice identifies that "Intentional" is not categorized as a specific type of COMSEC incident. In the context of COMSEC (Communications Security), incidents are generally classified based on the nature and circumstances surrounding them.

Unintentional incidents refer to situations where security measures fail due to accidental actions, such as mistakenly sending classified information over an unencrypted channel. Technical incidents involve failures related to equipment or software that compromise communications security, such as hardware malfunctions or software errors. Environmental incidents could pertain to natural phenomena, disasters, or other environmental factors that disrupt the availability or security of communications systems.

While intentional acts can occur, they are usually classified under malicious activities rather than as a distinct category of COMSEC incident. Thus, "Intentional" does not reflect a specific classification in COMSEC, making this choice the appropriate answer.