We're screwed

Daniel L. Byman and Kenneth M. Pollack:

The debate is over: By any definition, Iraq is in a state of civil war. Indeed, the only thing standing between Iraq and a descent into total Bosnia-like devastation is 135,000 U.S. troops -- and even they are merely slowing the fall. The internecine conflict could easily spiral into one that threatens not only Iraq but also its neighbors throughout the oil-rich Persian Gulf region with instability, turmoil and war.

They make a pretty good case for why we can't just leave now, present some pretty grim scenarios about what could happen next and make some suggestions -- some pretty good, some not so (more troops!) -- about how to manage it. But there is no prediction of a happy ending.