Waxing Political: Iran

I have a friend who works in Europe, and recently visited with him. We got into politics a little, and I completely agreed with him that Bush was a terrible president. He talked some about Iran, and said that China and Russia were the reaons the U.S. no longer has an overtly hostile intent to use military force, because China gets their oil from Iran, as does Russia. Something to that effect. I didn't fully understand the argument, and even said so to him, that we the regular folks don't get that perspective here. But it's planted a seed of curiosity in me, so in my free time I read up on China, oil, and Iran to see if I could find information related to China telling (not asking) the U.S. to back down. He also added that China can threaten because so many U.S. dollars are in their foreign currency reserves, the result of an imbalance of trade.

More as I think about it... does anyone have comments, or information that puts me closer to the truth?