A US military official has said children have been used in a bomb attack in Iraq, raising fears that insurgents are using a new tactic.
Suicide attacks continue but are less effective
Gen Michael Barbero said a vehicle stopped at a checkpoint was waved through because two children were seen in the back, but was then detonated.
Militants were changing tactics in response to tighter security, he said.
Five people including the children died and another seven were injured in the attack, in Baghdad on Sunday.
Gen Barbero said there had been also two adults in the car. They parked it near a market, abandoned it with the children inside and apparently detonated it.
The two children died, along with three civilians in the vicinity, officials said.
The children's identity is not known, nor their relationship to the adults.
Gen Barbero said it was the first time he had seen a report of children being used in bombings.
"The brutality and ruthless nature of this enemy hasn't changed," he said.
"They are just interested in slaughtering Iraqi civilians, to be very honest."
The apparent new tactics have come as more US forces are sent into Baghdad as part of a security crackdown.
Gen Barbero said that car bombs and suicide attacks have become more frequent but were less effective as they were often stopped checkpoints.
The use of chlorine bombs was another example of how tactics were changing, he added.
Several incidents involving chlorine have been reported in different parts of Iraq in recent months, prompting fears of a further escalation of conflicts between rival groups.