Major Mike Slocum, the 101st Aviation Brigade's Watch Officer, told an AFP correspondent on the ground that a fleet of Black Hawks, Chinooks and Apache helicopters were involved in transporting more than a battalion's worth of soldiers into the outskirts of Karbala.

"Basically they are on the ground to go through and secure the highways and supply routes, and also they are looking to squelch any paramilitary threat in the area," he said.

Slocum said the helicopters encountered little resistance and that the infantry troops would secure the outside of the city before moving in.

He said the operation to secure Karbala, a major Shiite Muslim town less than 100 kilometres (60 miles) south of Baghdad, was similar to the just completed campaign in Najaf, which he described as successful.

Najaf lies a further 80 kilometres (50 miles) southwest of Karbala.

SPACE.WIRE