If you want a semi-historical platform to launch this hypothetical scenario from, Rudolf Hess would be a good example. He was imprisoned, along with other nazis, in a prison in West Berlin shortly after WWII. It was agreed that the different allied powers would take turns guarding this prison as long as prisoners remained. Fast-forward to the Cold War era, and that agreement had an unintended consequence: it gave the USSR a precious foothold in West Berlin. Thus, they vetoed every request for Rudolf Hess's release, until he died in 1987. He had been the lone inmate of the 600-cell prison for more than 20 years.

Now for an alternative history twist: the Cold War never ends, and Rudolf Hess is kept alive as a brain in a vat for thousands of years, with the Russians and the Americans continuing to take turns guarding him so that both sides can cling to that sliver of West Berlin.

Hell that pretty much straight up happens in Neuromancer, which is considered to be the codifier/originator of a huge portion of the tropes that make up cyberpunk as a genre.