Siting choice may have been as much a question of politics as anything else.

If the goal of the shield is to defend Europe from a missile strike launched from European Russia or the Middle East, targeting missiles at the higher end of the boost phase and or in the mid phase, than anywhere in Eastern European territory would probably be about the same value in technical terms.

In political terms, any effort that degrades the effectiveness of Russia's nuclear arsenal was bound to catch grief from the Russians. We could have deployed it in Des Moines and still drawn criticism. Russia has been spending billions but has not focused most of those dollars on their strategic arsenal -- so this adds another expense and is bound to annoy.

So, why Poland? Poland has been stauch in support of the USA and the WoT throughout the Bush administration. Other things being equal, politics said it was time to give the Poles a high dollar payback. They earned it.