The Defense Intelligence Agency (DIA) is an external intelligence service of the United States federal government specializing in defense and military intelligence. 

A component of the Department of Defense (DoD) and the United States Intelligence Community (IC), DIA informs national civilian and defense policymakers about the military intentions and capabilities of foreign governments and non-state actors. It also provides intelligence assistance, integration and coordination across uniformed military service intelligence components, which remain structurally separate from DIA. The agency's role encompasses the collection and analysis of military-related foreign political, economic, industrial, geographic, and medical and health intelligence. DIA produces approximately one-fourth of all intelligence content that goes into the President's Daily Brief. 

DIA's intelligence operations extend beyond the zones of combat, and approximately half of its employees serve overseas at hundreds of locations and U.S. Embassies in 140 countries. The agency specializes in collection and analysis of human-source intelligence (HUMINT), both overt and clandestine, while also handling American military-diplomatic relations abroad. DIA concurrently serves as the national manager for the highly technical measurement and signature intelligence (MASINT) and the Defense Department manager for counterintelligence programs. The agency has no law enforcement authority, but it is sometimes portrayed so in American popular culture.
Where are half of it's employes located?
 overseas