What's fascinating is how close we came to having a serious military presence in human spaceflight. The US were planning on launching the "Manned Orbital Laboratory" (MOL) in the '60s but it ended up being sidelined by improvements in spysats as well as budget overruns before it was finally cancelled. The US continued dabbling with military uses of crewed spacecraft through Skylab and the Shuttle program but for the most part it was pretty boring stuff. Meanwhile, the Soviets launched the Almaz series of stations in response to the MOL program. However, out of 3 stations only one was able to operate successfully. Also, as in the US improvements in automated surveillance satellites undercut much of the program's justification for existence.

But then you get to the '80s. The US has the Shuttle which performs both civilian and military missions, of unknown scope. The Soviets decide they need a Shuttle too so they build their own (Buran). The Soviets also respond to the bluster of Reagan's announcement of the "Strategic Defense Initiative" to initiate a program to build weapons platforms in space, starting with an enormous 80 tonne military station replete with a laser canon. This vehicle, Polyus or "Skif-DM", ends up re-entering during launch due to a malfunction in 1987, completely changing the whole arc of spaceflight history. Meanwhile, the Buran, launched by the same heavy lift rocket Energia, launches a year later in an uncrewed flight. The Soviets slowly realize that there isn't some magic to the Shuttle and it's actually not that great of a vehicle (notwithstanding the cool factor) so they don't pursue the use of it much, then the following year the Berlin Wall falls, 2 years after that the Soviet Union collapses, and 2 years after that the Shuttle-Mir program begins, with Russian cosmonauts flying on the Shuttle, Shuttles visiting the Russian space station, and so on, as a prelude to the ISS.