Carter--Cold War ongoing, Soviet Union hostile.
Bush--Cold War over, Russians "cooperative."
I think RW2 is saying that Russia is still an enemy, not "cooperative." And he also is alarmed that we may have less nukes than Russia, even though we have enough.
The problem with both Reagan and the two Bushes is that they have been too optimistic and idealistic about missile defense. They have all seemed to think that if you build a good enough shield you won't need any deterrence at all. It is one thing to not rely exclusively on MAD. It is another to think we don't need an offensive capability. In order for missile defense to be effective, the enemy has to believe that you have a second strike capability.