The National Security Agency (NSA) is an intelligence organization of the United States government, responsible for global monitoring, collection, and processing of information and data for foreign intelligence and counterintelligence purposes – a discipline known as signals intelligence (SIGINT). NSA is concurrently charged with protection of U.S. government communications and information systems against penetration and network warfare. Although many of NSA's programs rely on "passive" electronic collection, the agency is authorized to accomplish its mission through active clandestine means, among which are physically bugging electronic systems and allegedly engaging in sabotage through subversive software. Moreover, NSA maintains physical presence in a large number of countries across the globe, where its Special Collection Service (SCS) inserts eavesdropping devices in difficult-to-reach places. SCS collection tactics allegedly encompass "close surveillance, burglary, wiretapping, breaking and entering".