Several military Soyuz spacecraft models were planned, but none flew in space. These versions were named Soyuz P, Soyuz PPK, Soyuz R, Soyuz 7K-VI, and Soyuz OIS (Orbital Research Station).
The Soyuz P (Perekhvatchik, Interceptor) space interceptor and Soyuz R (Razvedki, intelligence) command-reconnaissance spacecraft was proposed in December 1962 by Sergei Korolev.
In the initial draft project, the Soyuz P would use the Soyuz 9K rocket stage and Soyuz 11K tanker spacecraft to conduct a series of dockings and re-fueling operations. The complete complex would then could conduct intercepts of enemy satellites in orbits up to 6,000 km in altitude.
The Soyuz-R system consisted of two separately launched spacecraft, including the small orbital station 11F71 with photo-reconnaissance and electronic intelligence equipment and a Soyuz 7K-TK for crew transport.
Initially the Soyuz P was designed for piloted inspection and destruction of enemy satellites. It was intended that the Soyuz would rendezvous with the target satellite. To minimize risk to the crew, a new version, Soyuz PPK (pilotiruemovo korablya-perekhvatchika, manned interceptor spacecraft) was later proposed.
The Zvezda (star) station was based on a radically modified Soyuz. Objectives were manned earth observation, orbital inspection and destruction of enemy satellites. Zvezda would be powered by two plutonium radioisotope generators and had a recoilless gun for defense. It was designed for shooting in a vacuum and defending the military research spacecraft from enemy satellite inspector and interceptor satellites. The gun was aimed by maneuvering the entire spacecraft. A special gunsight was installed in the descent module for aiming the gun. A forward docking apparatus to allow docking with Almaz was also included. Work on Zvezda was canceled in 1967 with a single prototype in advanced stages of construction.
Cosmonaut training for the VI began in September 1966. The cosmonaut group selected included commander Pavel Popovich, pilot Alexei Gubarev, flight-engineers Yuri Artyukhin, Vladimir Gulyaev, Boris Belousov, and Gennadiy Kolesnikov. Popovich-Kolesnikov and Gubarev-Belousov were the prime crews, with the other engineers acting as reserves and then assigned to later crews.