Final answer:
The Strategic Automated Command and Control System (SACCS) is the primary network used to transmit emergency action messages from the NMCC to field commanders.
Step-by-step explanation:
The primary network used to transmit the emergency action messages (EAM) generated by the National Military Command Center (NMCC) to the warfighting commanders in the field is the Strategic Automated Command and Control System (SACCS). SACCS is responsible for transmitting time-sensitive and critical messages related to national security. It provides a secure and reliable communication channel for the NMCC to effectively coordinate with the warfighting commanders.