Iraqi police say two car bombs in a Shi'ite district of Baghdad have killed at least seven people and wounded more than 25 others. The Iraqi commander in charge of the Baghdad security plan has defended the operation's success, following an internal U.S. military report indicating progress in securing neighborhoods in the capital has been slow. Meanwhile, U.S. military says four American soldiers have been killed in Iraq, pushing the U.S. death toll in more than four years of war in the country toward 3,500. VOA's Barry Newhouse reports from northern Iraq.

Two massive car bombs exploded near Baghdad's most revered Shiite Muslim shrine, located in the capital's Kazimiyah district. Witnesses said the blasts appeared to target civilians in the Shi'ite majority district.

Large vehicle bombs continue to obstruct American and Iraqi efforts to secure the capital. In several raids Wednesday targeting al Qaida-linked car-bomb networks, U.S. forces killed two suspected terrorists and captured 10 others.

A U.S. military report this week said efforts to secure the capital are moving more slowly than expected. An Iraqi military spokesman for the Baghdad security plan defended the operation, saying troops are changing tactics to clear violent neighborhoods.

General Qasim al Muslawi says commanders are rotating troops out of troubled neighborhoods and replacing them with larger numbers of soldiers. He also says he needs more cooperation from citizens to help limit the ability of terrorists to move around.

The success of the Baghdad security plan is key to stabilizing the country and strengthening Iraq's divided government. But many Iraqi and American lawmakers remain skeptical of its chance for success.

On Tuesday, a faction of lawmakers loyal to anti-American cleric Moqtada al-Sadr pushed through legislation that will require Iraq's government to seek the approval of parliament before extending the U.N. mandate for U.S. forces. The current mandate expires December 31.

In an interview with an American radio network, NPR, the U.S. Ambassador to Iraq Ryan Crocker said if American forces leave Iraq, the situation could worsen.

Nouri al-Maliki (file photo)

The prime minister says some countries think Iraq is weak and the current situation is a chance for them to gain power by supporting militia groups. He says one, strong unified Iraq is the best thing for everyone.

Sectarian attacks continue to hurt efforts at unifying the country's numerous religious and ethnic groups.

On Tuesday, near the Shi'ite holy city Najaf, a close aide to the country's most revered Shi'ite cleric Grand Ayatollah Ali Al Sistani was killed at home. Police said unidentified gunmen drove by the house of Raheem al-Hasnawi, shooting him dead.