I tend to mostly agree with Bakerstreet. Iran cares less about Pakistan, India and China. None are a direct threat to them, and again, neither are american allies to the north and west. But they are a counter balance to Israel and would give them a carte blanche for non-nuclear agression.
Except, the wild card here are the mad mullahs. They really have no conception of global politics, and since they ultimately control Iran, they could go off half (or full) cocked and use them. I think that joker in the deck is what has most of europe and Israel most concerned. And I beleive with good reason.