At the beginning of the 1960s, the Soviet government adopted a policy of assigning Kosmos names to all military satellites reaching orbit. In addition, any non-military payloads, whose mission was supposed to remain secret, were also lumped together with the Kosmos series. Also, some test missions, which had flown before their programs were publicly announced, also became the part of the Kosmos series. Military satellites include Oko early warning satellites, US-A & US-P ocean surveillance satellites, Strela and Garpun communications satellites, Parus & GLONASS navigation satellites, Tselina electronic intelligence satellites, as well as optical reconnaissance satellites like Yantar.
The United States also assigns a "USA" number to mask its military satellites.