The National Security Agency (NSA) provides support to the counterintelligence missions of the combatant commands and Services, including deployed and deploying Joint Task Forces, through its signals intelligence (SIGINT) and information systems security (INFOSEC) organizations.
(From: http://webapp1.dlib.indiana.edu/virtual_disk_library/index.cgi/4240529/FID521/pdfdocs/jel/jp3_33/OTHER/2200ns.pdf)
