I'm aware of the geography (more than Bush was, I think) and have noted it here and at wotmania. It's part of why the Iraq invasion was so stupid, because it totally undercut the Khatami governments efforts to democratize and open relations with the West in general along with America specifically. Against the backdrop of Saddams non-existent and North Koreas highly successful nuclear weapons programs it made Ahmadinejads "we need nukes!1!1" policies very appealing for the same reason it made Khatamis insistence America was an honest broker for peace so non-credible.

China isn't going to let Russias desire to sell Iran finished products rather than letting Iran independently produce them stand in their way. It's one of the few reasons Russia's a better partner for peace; they see it as in their interest to keep rogue states perpetually beholden to them, while China seems to think nothing of setting them up with all the military hardware they want in the interest of both profits and complicating things for their supposed American allies. That radicals in Pakistan might decide to send their nukes back to them over treatment of Muslim extremists in China is rather cold comfort for everyone. But don't kid yourself that if it comes down to it China's not willing to exercise a unilateral veto of efforts to prevent Iranian nuclear weapons.

The issue seems to be whether Russia and China think it more advantageous to work with us against common foes in each other, or work with each other against a common foe in us. And as the worlds top political, economic and military power, the answer seems fairly clear as they prevent the only obstacles to limiting nuclear proliferation, the only real source of that proliferation. I think their position as a Commonwealth state and China giving Pakistan the bomb will keep India out of such an arrangement (though Indias growing economic might, a hostile nuclear power on its border and decades old alliances with us and the British may make the term "quagmire" inadequate; think of it more as a nuclear free for all that may make Kashmir long for the days all it had to fear was bombers and tanks. ) But right now it's in the interest of China and Russia to topple the king of the mountain, and aiding the nuclear ambitions of radical states serves that interest on both a military front from which they can be largely free of involvement and an economic front where they compete with no one save each other as nuclear weapons merchants.