In a previous trip, McCain touted the fact that he was able to walk through al-Shorja market as a sign that the surge had succeeded. On his current trip, the market was off-limits, as John King explained:

We got close to that marketplace today, Jim, but our own security advisers here in Iraq did not want us to go there. They didn’t believe it was safe for an American to be in that area. We were in a thriving marketplace nearby... That one marketplace, as a matter of fact, you do see Iraqi police, you do see the Iraqi army, but in truth, that area is controlled by the radical cleric Moqtada al Sadr’s Mahdi army.

Apart from the obvious embarrassment, it strikes me as more revealing that King understands that the distinction between the "Iraqi" army and the Mahdi army is not always very clear.