The shield was always about Russia. Iran does not possess rockets which could be a threat to Europe or the US. The Russians knew this and this is why they offered a military base close to the Iranian border. Anybody remember this? They must have laughed a lot in Moscow... I think they hoped that the Russians would decline the offer to collaborate on the shield. Why should they do so in the first place? And now the Russians did a very clever move. They have nothing to loose, can build up their missile defenses without anybody being in the position to criticise them and if they lose interest they can still run away without taking any drawbacks. My respect! Don't mess with the Russians!