You mean like our Stars Wars program in the 80s? :-)
Honestly, I've never been afraid of certain nations possessing nuclear weapons, as the cost of launching them (namely retaliation fire from our own nukes) would far outweigh the benefit of their use. In other words, nukes cannot really obtain anything (besides fear) for that nation because they would equally be obliterated as soon as their launch button was pressed.
What does worry me though, are these rogue terrorist groups that can come into possession of such capabilities from nuclear powers and can freely launch an attack with no immediate reprocusions, as they are not affiliated with any particular nation state and thus cannot be targeted with equal force.
So, unless Russia is going to be handing these nukes over to Al Qaeda, I'm not terribly worried at the moment.
The doctrine of MAD.
Mutual Assured Destruction
And terrorists don't give a damn which is why we need to assure their immediate destruction.