by Mike Wooldridge
BBC News, Baghdad
The US military in Iraq has given new details of an attack last week in which five US soldiers were killed.
The militants got by an Iraqi police checkpoint before the attack
Four of them were abducted by militants posing as an American security team.
They travelled in the kind of vehicles often used for US government convoys, Wore US-style uniforms and carried US-style weapons.
Initially the military said all five soldiers were killed repelling an attack on an Iraqi government compound in the Shia holy city of Karbala.
According to the new account, US military officers were attending a meeting in the compound when the convoy of at least five sport utility vehicles impersonating Americans entered and killed one US soldier.
There was a series of explosions and in the melee, the attackers then set off again with four captured US soldiers.
They drove into a neighbouring province and then abandoned the SUVs.
Iraqi police, by now in pursuit, found the vehicles.
The attack on the US troops is believed to be unprecedented
Two US soldiers were found handcuffed together in one of the SUVs, shot dead.
A third American soldier lay dead on the ground.
The fourth was still alive despite a gunshot wound to the head but died shortly afterwards.
Such a brazen attack is believed to be unprecedented, and the US military say the militants bypassed Iraqi police to reach their goal.
The Americans say they are not only trying to determine who carried out the attack but also the reason for the breakdown in security at the government compound.