40s era weapons were atomic, not nuclear.
Atomic weapons are not fission weapons where nuclear are fusion weapons.
Nuclear weapons cover both fusion and fission weapons.
In the height of the cold war era a suitcase nuke being sneaked into the US was the stuff of spy novels. Today is a real possibility.
That depends on what you mean by that.
"suitcase nuke" was shop talk for an ultra portable, not nesscessarily literally a nuke in a suitcase.
That is 80s tech.
The point is that nuclear weapons aren't exactly bleeding edge tech. And they aren't trying to make them with technology from those eras either.