To gain strategic control of the Middle East, due to it's central location.
Afghanistan is too far away from the region. By being centrally located The US military in Iraq threatens Iran to the East and Syria to the West. Additionally, the US position provides protection for Israel and Saudi Arabia.
The other strategic concern of the Middle East is simple: Oil. Stopping the post-Shah Iran from dominating the Oil reserves of the region has been the goal of the US since 1979. Unfortunately, the Bumbler in Bush only strengthens the repressive Iranian Governments position when he ineloquently slurs his Axis-of-Evil speeches and threatens an attack of Iran.
So, let's dispose of the those romantic notions of Bringing the Light of Democracy to the region or the fearmonging of Terror and Weapons of Mass Destruction.
The plight of the Kurdish people clearly illustrates our commitment to stop the spread of Democracy and self-determination. The Kurdish people will never be allowed to form a Nation-State for themselves. The government of Turkey is conducting a war on the Kurds (ostensibly their own people) in Eastern Turkey and will engage in full blown war (using F-16s sold to them by War profiters from the US) if the Kurds attempt to create the nation of Kurdistan.
And this is where the truth of the UN comes into play. The UN only cares for it's members who are (and this may surprise some) not human individuals but Nation-States. And it is in the interests of Nations to stop new members from being created. The grossness of the UN is for another day.
21 minutes ago