Nearly 20,000 people were in Iraqi-run prisons, detention camps, police stations and other holding cells as of the end of March, according to a U.N. report issued last month, an increase of more than 3,500 from the end of January. The U.S. military said late last week that it was holding about 19,500 detainees, up more than 3,000 since the U.S. and Iraqi governments began implementing the security plan in mid-February.

Back to Tom Ricks' book Fiasco again, this is one of the things that caused such a god-awful mess in 2003-4 that got us where we are now.

At this point, I'm sold. The "surge" is going to make Iraq into an even worse bloodbath for us than it was before and guarantees, we will not have a stable, allied Iraq anytime soon, and probably not ever. Getting out by next spring/summer won't do it. If we simply picked everything up right now and got the hell out of Dodge in the middle of the night like the Colts leaving Baltimore, we'd be better off.

New Detainees Strain Iraq's Jails - washingtonpost.com