Ultimately piracy in Somalia is unlikely to stop until chronic instability, caused by rival warlords and Islamist fighters, is tackled.

ECONOMIST: Piracy and private enterprise

And what we're being told by local Iraqi police who are here with the American forces is that they're doing that to make sure that the Mahdi Army fighters cannot be resupplied, and to also stop Mahdi Army fighters from leaving Sadr City and going to other areas and spreading the instability.

NPR: U.S. Troops Killed as Fighting Reignites in Sadr City