The US has very little to gain by provoking Rusia back into Georgia and a lot to lose.
The last thing the US would want is to give Putin the excuse to gain more of a stranglehold on the Black Sea coastline.
Oh, and it's quick difficult to blockade the Iranian coastline as it extends out past the Straits of Hormuz into the Arabian Sea / Indian Ocean; whereas, by minining the Straits to buggery the Iranians could easily stymie shipping routes from the Gulf of Arabia - extremely irritating and inconvenient for the US and her allies.
Also, the only thing the Russians and Iran have in common is a mutual distaste for the current US regime. Whatever pipelines may be opened up under the Caspian Sea, it's more than highly unlikely that Russia would seek to arm such a volatile neighbour in such a way that she would not be able to bring Iran to heel. Conventional weapons - certainly, Anti Satellite missiles - quite possibly, Nuclear weaponary - not a cat in hell's chance, Iran would be far more likely to acquire any technology on the Black Market, after all, the Russian military is no longer skint, and as they are fully signed up with JACIG, they are required to account for the hardware and it's storage.
When it comes to the Chinese, I think the West has less to fear than traditionally thought. One thing that the belated Industrial Revolution has done for the country is convince the powers that be that trade is the real route to Global power, and any activity that could compromise the trading environment will be re-examined very closely indeed. That's not to say that China will turn into a paragon of virtue, but certainly a softening of foreign and military policy and lip service towards the Nepal situation and Human Rights Issues.