The lack of a disengagement policy or any longer-than-a-month-strategy for Iraq is mirrored with Camp XRay / Guantanamo:
America gets very little useful intelligence from the place (according to intelligence officials stationed there) and keeping it running is incredibly damaging to Americas reputation but they cannot dismantle it because it would be an admission that it was sold to the American people under false pretenses and running it wasn't justified.
So, like so many other cases (keeping known innocent women locked up in Abu Graib) they carry on with a failing system and will keep doing it until some snaps - either they are physically forced to stop by someone else or it becomes so politically damaging because of the pressure from home that abandonment becomes the least worst option.