But now in Iraq, the Army has quietly decided to try going it alone for the important surveillance mission, organizing an all-Army surveillance unit that represents a new move by the service toward self-sufficiency, and away from joint operations.

Senior aides to Defense Secretary Robert M. Gates say that he has shown keen interest in the Army initiative  much to the frustration of embattled Air Force leaders  as a potential way to improve battlefield surveillance.

The work of the new aviation battalion was initially kept secret, but Army officials involved in its planning say it has been exceptionally active, using remotely piloted surveillance aircraft to call in Apache helicopter strikes with missiles and heavy machine gun fire that have killed more than 3,000 adversaries in the last year and led to the capture of almost 150 insurgent leaders.

The Army aviation task force became fully operational last July with headquarters at Camp Speicher, in the north-central city of Tikrit, and focuses its efforts on insurgents planting roadside bombs. But it also has located and attacked insurgents in battles with American and Iraqi troops, and has supported missions of the top-secret Special Operations units assigned to capture or kill the most high-value targets in Iraq.

The battalion is called Task Force Odin  the name is that of the chief god of Norse mythology, but it also is an acronym for “observe, detect, identify and neutralize.” The task force of about 300 people and 25 aircraft is a Rube Goldberg collection of surveillance and communications and attack systems, a mash-up of manned and remotely piloted vehicles, commercial aircraft with high-tech infrared sensors strapped to the fuselage, along with attack helicopters and infantry.