Huh. I would have thought (again, not an expert) that Trump would be referring to "defensive" ballistic subs (I normally think of "attack" subs as being the hunter/killers, which try to find the enemy's ballistic subs), and the deployment would be into the baltic (although the mediterranean also makes sense). I guess if you think about it as "US deploys hunter/killer attacks closer to Russian assets" (black sea navy, or near major port cities like Vladivostok, or areas like Crimea or the Russian area near it), since I imagine they have the capability to attack cities, maybe it makes more sense to change their deployment? But in that case, why wouldn't he deploy aircraft carrier groups?

I guess we (the public) will probably never know for sure.