WHO IS KEEPING THE AMERICANS IN IRAQ?

Ironically, Iran's long-term position could weaken when the United States draws down its forces. At first, the U.S. withdrawal will expand the power vacuum and Iran will try to fill it, but the limited chaos Iran foments can easily become uncontrolled. Iran's economic and military power is limited, and Iran's theocratic model of governance has little appeal for most Iraqis. Even many Shiite militants have at times been hostile to Iran, and respected moderates such as Grand Ayatollah Ali Sistani are careful to maintain their distance from Tehran. Sunnis already rage against perceived Iranian dominance.
http://www.washingtonpost.com/wp-dyn/content/article/2007/02/16/AR2007021601708.html?nav=rss_print/outlook