Related Event: Iraq in Transition

A top US Defence Department general said on Wednesday that the 21 Marines killed in northern Iraq this week were trying to contain "a very lethal and, unfortunately, adaptable enemy" operating in towns along the Euphrates River.

Brigadier General Carter Ham is the deputy director for operations at the US Joint Chiefs of Staff.

"They are dangerous and they certainly have a capability, but as to whether or not they have an ability to freely operate in that area, I think not. Because of the simultaneity of operations that multinational force West is conducting they don't have that freedom of movement and I think that is one of the contributing causes to these number of direct contacts that are occurring."

A Marine amphibious assault vehicle on patrol during combat operations near the Syrian border hit a roadside bomb on Wednesday, killing 14 Marines.

It was one of the deadliest single attacks in Iraq against American forces. Ham declined to provide details of Wednesday's attack, saying it was too early in the investigation.

Wednesday's bombing came two days after seven Marines died in the same area during combat with insurgents.

Ham speculated that the number of confrontations with insurgents in the region was increasing due to the effectiveness of coalition forces in denying safe havens.