I would suggest that the more capable the US ABM system becomes, the more inclined they (US) may be to have a shared reduction in strategic weapons, it smacks of a win-win situation to me.
There's no talk of non-strategic, the Russian's (NS) arsenal has little immediate impact (excuse the pun) on the US, that's Europe's problem, whilst the US may be content that they can deploy theirs globally by a variety of means.