SO this isn't as hard as it might seem at first glance.
simply tech rush nuclear - id suggest using the nuclear blueprints on the second two nuclear techs, and completing all the research enhancing techs before starting the nuclear techs.
you want to eventually trigger a civil war, so you want to stay away from the ideology focus tree till later on, you need the commie or fascist political adviser, which you can only get with the appropriate focus.
once you have your nuke tech, some strategic bombers and some fighters, you just need to trigger a civil war, once that starts nuke the rebelling area and achievement unlocked.