Suicide bombers have targeted a Baghdad military headquarters killing 12 people.
The blast came two weeks after an attack on the same site pointed to the failure of Iraqi forces to plug even the most obvious holes in their security.
Baghdad has been on high alert as the US declared the official end to its combat operations in Iraq last week, yet the militants still managed to hit an obvious target in the centre of the city that has been struck very recently.
On August 17, an al Qaida-linked suicide bomber blew himself up at the same east Baghdad military headquarters and killed 61 army recruits in the deadliest act of violence in Baghdad in months.
Iraqi military spokesman Major General Qassim al Moussawi said 12 people had been killed in the attack and 36 were injured. Five soldiers were among the dead.
A car bomb hit the building and exploded, and then gunmen assaulted the headquarters, battling with the building's guards in a 15-minute firefight in the middle of Baghdad, according to police officials, who said at least three militants were wearing explosives belts.
The bombers were heading to the building's entrance on foot but were shot by the guards before they could trigger their devices. One was only wounded and has been taken into custody.
Defence Ministry spokesman Major General Mohammed al Askari confirmed that some of the gunmen were wearing explosives belts. He said they were planning a second blast.
The latest attack is an embarrassment for officials in the capital where security has been high in recent days as insurgents intensify their strikes on Iraqi police and soldiers to mark the change in the US mission.
The building attacked is the headquarters for the Iraqi Army's 11th Division and an army recruitment centre.