According to my knowledge, borders between individual SSR's were generally open and consisted just of signs during Soviet times. With the breakup of the union, the problem of border security arose. Now, only the Russian-Belorussian border is free to cross, other borders being controlled borders with toll checkpoints and long queues.
My question is:
- How did the border regime between the individual SSR's change during and after the breakup of the USSR? When were border controls imposed?
- How did the first provisional border control posts look? How were roads changed to cater for the need to control traffic?