Why is America allowing Iran to take over Iraq ,after so many GI�s died there ?

Iraqi officials are boldly admitting ,that they don�t want Americans over there. They would rather have one of America�s largest haters , ( IRAN ) run their country , after the with-drawl Obama has promised. The American government has killed their soldiers for nothing. What did the soldiers and their family members gain ,other than a disability check and a casket !