Basra breakdown

TPM does a nice job of spelling out just what the hell is going on in southern Iraq.

Who's shooting at who, why it's spilling over into Baghdad, and why this shouldn't be much of a surprise to people.

...now it's chaos, as the operation deepens in Basra and there are clashes in Baghdad -- where the Iraqi forces are also attacking "special groups" (as an American official calls them, meaning Shiite militias with Iranian backing) with American support. Shiite insurgents have responded in part by firing rockets into the Green Zone. There's also a good deal of violence between the rival Shiite militias in Baghdad and elsewhere.

[snip]

As the Post observes it's an awkward time for the biggest test yet of the preparedness of the Iraqi forces: "It was unclear why U.S. forces would take part in a broad armed challenge to Sadr and his thousands-strong militia on the eve of Petraeus's assessment, which the Bush administration has said would greatly influence its decision on whether to draw down troop levels."

It's a hairball, to be sure - but TPM adds some clarity.