By Peter Graff

FORWARD OPERATING BASE KALSU, Iraq, Aug 16 (Reuters) - U.S. forces launched an airborne assault on a desert compound south of Baghdad on Thursday, the first air strike in a major new offensive.

A company of airborne infantry struck villas in search of Sunni Arab militants. The assault was a first part of operation Marne Husky, itself part of a countrywide push announced this week against both Sunni Arab and Shi'ite militants.

Major-General Rick Lynch, commander of U.S. forces south of Baghdad, told Reuters on Wednesday that about 4,000 of his men would be involved in the operation and would use air strikes and air-mobile infantry units to attack insurgents in the Tigris River valley south of the Iraqi capital.

Pointing on a map to the palm groves south of Baghdad in an area known as Arab Jabour, he said his troops had already pushed out many Sunni Arab militants in the past month and now planned to strike those who escaped southwards.

Washington sent an additional 30,000 troops to Iraq this year and has pushed them from big bases into neighbourhood outposts in an effort to reduce sectarian violence and defeat both Sunni Arab insurgents and hostile Shi'ite militia.

Operation Marne Husky involves sending infantry into territory where U.S. forces had not had a presence in the past, in an area south of Baghdad U.S. troops call the "Triangle of Death".

"Tonight it's going to be the first time in about a year they've seen coalition forces. They've had aircraft flying overhead. But they can't hide from infantry kicking down the doors," Lynch said.

The U.S. commander in Iraq, General David Petraeus, is due to report to Congress next month on the success of his strategy.

This week U.S. forces announced the launch of a countrywide offensive, operation Phantom Strike.

On Tuesday they announced the first part of Phantom Strike, known as operation Lightning Hammer, which began with an airborne assault on the Diyala River valley north of the capital.

A spokesman for the unit said the soldiers were airlifted out before dawn having captured five suspected militants, destroyed homemade explosives and uncovered a cache of weapons.

AlertNet news is provided by