I really don't think the US will necessarily tell Poland exactly what missiles they will be installing on their territory, and the bases are supposed to be entirely under US control, with no Polish oversight. It makes sense for Russia to be suspicious since the Iranian excuse is transparently false, and it would also make sense for Poland to be suspicious.

Now that Tusk has accounced he will be talking to the Russians directly about this  there's a good chance the plan will never be implemented.

We have met the enemy, and he is us — Pogo