Most people don't knows this, USA don't buy Middle East oil, America consume great deal of oil from her own outputs along with oil import from Canada and Venezuela.
The Petrol Dollar is the keystone to undo American economic and Western power grip around the world.
The reason why Iraq, Libya, Syria and Iran are being target for regime change is because all these country are removing the Petrol Dollar as their base currency for their oil trade. You will never see physical attack into North Korea, Cuba, Mynamer and any dictator who can't threaten the Western domination of World Trade Currency(US Dollar).
Iraq removed the US dollar and settle her oil trade in Euro.
Libya talking of removing the US dollar and settle her oil trade in Gold.
Iran is now removing the US dollar and settle her oil trade in all currency including Euro, Russian Ruble, Chinese RMB and bartar system.
Syria is just a dollar step to Iran.
Russia and China knows this situation and they are defending Syria and Iran because they knows the Chinese theory, "when the gum is demanded, the teeth will feel the chill".
Syria and Iran is the last defense against the Western grip on the global power.
Iran is also the keystone to undo the Western domination by attacking and weaking the Petrol Dollar.