The interior minister, meanwhile, said his office believes militant leader Abu Musab al-Zarqawi was wounded, while an Internet statement claimed that Iraq's most feared terrorist group had appointed a deputy to fill in for the Jordanian.
Abu Musab al-Zarqawi injured: Reports
At least 11 Iraqis died in violence nationwide, including a child, during clashes between US forces and insurgents in the northern city of Tal Afar.
Among those killed were a university professor, slain in a drive-by shooting in Baghdad, and three policemen who died in a car bombing in the capital.
The military also said a US Marine died of wounds sustained a day earlier during the launch of an anti-insurgent offensive involving about 1,000 US troops in the western city of Haditha.
The security cordon next week would be followed by similar anti-terrorism moves across the country, part of an effort to shift the government stance toward the insurgency from a defensive to an offensive position, said Interior Minister Bayan Jabr and Defense Minister Saadoun al-Duleimi.
"Next week, we will have a strong and safe cordon around Baghdad like a bracelet that surrounds the hand. We will not allow anyone to cross this cordon," al-Duleimi said.
Jabr said there would be 675 checkpoints plus mobile checkpoints to try to deter assailants in areas where attacks are frequent and cars are often booby-trapped.
"You will witness unprecedented security measures and none familiar to you," he said. "We have to work together, government and people, because security is for all the citizens, not just the government."
The ministers said Baghdad would be divided into two sectors and 15 districts where police and emergency personnel would operate 24 hours a day.
"We will stand against anyone who tries to kill Iraqis and we will impose the law by adopting all tough measures," Jabr said.
"We do believe that we are going to give Iraqis what they have lacked," al-Duleimi said, an apparent reference to the poor security available throughout Iraq since the collapse of Saddam Hussein's regime.
The latest statements concerning al-Zarqawi follow recent rumors and claims he had been wounded, possibly by a bullet in the lung, or perhaps even had died.
Interior Minister Bayan Jabr told reporters he has information that al-Zarqawi was, indeed, wounded, but that he wasn't sure how seriously.
"We are not sure whether he is dead or not, but we are sure that he is injured," Jabr said.
An Internet statement claimed the al-Qaida in Iraq terrorist group had appointed a temporary replacement for al-Zarqawi. The statement was quickly denied in another Web site claim that disputed Abu Hafs al-Gerni had taken over.
The authenticity of either Internet statement could not be verified, although the second --denying any deputy had been appointed -- was posted in the name of the person who usually handles the group's Web site claims and announcements.
Iraq: Sadr's aides meet Sunnis
Wednesday's first statement identified al-Gerni as "deputy of the holy warriors," saying he was "known for carrying out the hardest operations, and our sheik would choose him and his group for the tough operations."
But the Web site statement signed in the name of al-Qaida in Iraq's so-called spokesman, Abu Maysara al-Iraqi, denied the group had appointed al-Gerni "or anyone by any other name."
Experts on Islamic militants told The Associated Press that al-Gerni is a Saudi who has been al-Zarqawi's military adviser and is the emir, or prince _ as senior commanders are called _ of the military committee of al-Qaida in Iraq.
A car bomb exploded in northern Baghdad near a police patrol, killing five people -- three officers and two other Iraqis -- and wounding 17, according to police Lt. Haider Hussein and medic Naseer Hashim of Nour Hospital.
Unknown gunmen shot dead Iraqi army Capt. Awas Youssif Hassan in Khalis area east of Baqouba, 35 miles northeast of Baghdad. said army Col. Abdulla al-Shimary.
Separately, gunmen in a speeding car fired automatic weapons at a group of people driving to work in Baghdad's southern Risala neighborhood, killing four Iraqis, including a university professor and a translator working for the US military, said police Lt. Hussam Noori.
Iraqi security forces and Iraqis working with coalition forces have been repeatedly attacked by insurgents determined to bring down the country's US-backed government.
More than 1,000 US troops continued a sweep through Haditha, 140 miles northwest of Baghdad in the troubled Anbar province, for insurgents responsible for multiple attacks against coalition troops.
A child was killed when a mortar landed on his family home Wednesday, the military added.
The offensive, the second on a road to Damascus in less than a month, was aimed at uprooting insurgents who have killed more than 620 people since a new Iraqi government was announced April 28.
Another Iraqi child was killed Thursday during clashes between U.S. forces and insurgents in northern city of Tal Afar, 93 miles east of the Syrian border.
Tal Afar has been the scene of clashes since two explosions late Monday killed at least 20 people. Iraqi security forces closed access to the town and residents have said US forces backed by helicopters have since been clashing with insurgents.
Salih Haider Qado, director of Tal Afar hospital, said two children -- one about a month old and another about a year old -- were killed in fighting Wednesday, while four civilians were wounded.
It was unclear if the two incidents were related.
Last year, a nearly two-week siege of Tal Afar by US-led forces targeted foreign fighters holed up in the city, which is astride a smuggling route to Syria.
Mosul police Brig. Saed Ahmed said six militants were also killed, 20 injured and 26 suspected insurgents arrested when militants clashed with US and Iraqi troops Wednesday in the northern city.
(Associated Press writer Sinan Salaheddin contributed to this report in Baghdad)
