"Why would it be more effective to put the "shield" in Poland and the Czech republic than in Azerbaijan? Azerbaijan is right next door to Iran (the rogue state the US government is saying is its primary concern), while Poland and the Czech Republic are much further away."



You hit it exactly- the system works better if it has enough distance to actually track the attacking missile before it has gone overhead.

So, we could put it in Turkey, and have it never able to react in time or work, or in Poland and have it be effective.