From Wikipedia (of all places!):

The NSA maintains at least two WATCH centers:

1. National Security Operations Center (NSOC), which is the NSA's current operations center and focal point for time-sensitive SIGINT reporting for the United States SIGINT System (USSS). This center was established in 1968 as the National SIGINT Watch Center (NSWC) and renamed into National SIGINT Operations Center (NSOC) in 1973. This "nerve center of the NSA" got its current name in 1996.

2. NSA/CSS Threat Operations Center (NTOC), which is the primary NSA/CSS partner for Department of Homeland Security response to cyber incidents. The NTOC establishes real-time network awareness and threat characterization capabilities to forecast, alert, and attribute malicious activity and enable the coordination of Computer Network Operations. The NTOC was established in 2004 as a joint Information Assurance and Signals Intelligence project