There is an interesting development going on in the world as far as the US-petrol dollar is concerned. Some critics claim that one of the reasons for the invasion in Iraq was the fact that Saddam Hussein wanted to start doing oil trade in euros instead of US Dollars. Moammar Gaddafi had ideas of selling his oil in gold, and we now how the US-European humanitarian intervention caused the deaths of some 50,000 Libyans and the cruel murder of Moammar Gaddafi.

A while ago it was agreed upon that Russia and China would use their own currencies instead of the dollar for their oil and gas trade (1). Now, because of the US-sanctions against Iran some countries are forced to use other currencies as well. India is the most recent example of how more and more countries are moving away from the oil petrol dollar (2). 

India had already abandoned the dollar and used euros to pay for the Iranian oil (through a Turkish bank), but they intend to pay for the Iranian oil in Indian rupees. With these rupees Iran can buy Indian steel for their railways for example.

Iran and Russia have also started to trade their oil in their own currencies as you can read in 'Iran, Russia replace Dollar' (3). 

It is clear that the US is losing ground in the world. Not only are China, Russia and India against any military intervention or further sanctions against Iran, these countries are also moving away from the dollar as the standard currency to buy oil with on the international markets. For India, Iran is the second country after Saudi Arabia to get their oil from; For China, Iran is the third supplier (after Saudi Arabia and Angola) (4).
The US is an empire in decline: with failing military operations and a collapsing dollar in the oil sector.