The operation, Lightning Hammer II, is an extension of an earlier operation in Diyala province.

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The military said the operation "follows Lightning Hammer I ... to deny al Qaeda safe haven in the provinces" of Salaheddin, Nineveh, Diyala, and Kirkuk.

CNN: 26,000 U.S., Iraqi troops conduct offensive

The military said the original Operation Lightning Hammer -- August 13 to September 1 -- ousted militants from the Diyala River valley, northeast of Baquba, the capital of Diyala province.

CNN: 26,000 U.S., Iraqi troops conduct offensive