Sy Hersh has written a great article, available in the New Yorker (yes, that does mean it's long-- unlike The Economist, however, that also means it's worth it) on the web of relationships and power politics in the Middle East, focusing especially on Iran, Syria, Iraq, Saudi Arabia, Lebanon, and the US. It's a complex situation for sure, but a narrative that emerges almost immediately is that the US lunged headlong into an impossible strategic situation in Iraq, propelling its longtime enemies (and those of its allies) to increased power. The same action virtually forced us to take opposite sides in Iraq (i.e., the Shiite allies of Iran and Syria) from those we take everywhere else (the Sunnis-- specifically the Saudi royal family), thus making the situation even worse for everyone in the region... except Iran, the one player we want to screw over all others.
Now our #2 ally in the Middle East and #1 financier, Saudi Arabia, openly threatens to side with those currently killing the most US troops if we dare to leave.
Heckuva job, Dubya!