Bombings this week in Sunni areas of Iraqi have killed more than 100 people.
US forces hope that the wall will reduce militia attacks, allow for reconstruction.
The British CBS reporter had been held for two months in the southern Iraq city of Basra.
American forces in Iraq announced Monday ambitious public-works plans to win support in Sadr City.
US and Iraqi forces have been battling Moqtada al-Sadr's Mahdi Army there since March 25.
Bush announced Thursday that Army tours will be cut to 12 months.
In an interview, a member of the Islamic Army of Iraq speaks of his group's long-term goals.
Iraq's oil minister says the assault helped curb oil smuggling.