On April 9, the Department of Defense alerted four National Guard brigade combat teams for deployment in support of Operation Iraqi Freedom. Although deployment is planned to commence in December 2007, the onset will be based on conditions in Iraq at that time, said officials. The early alert provides predictability for family members and flexibility for employers of the 13,000 troops involved. DoD officials said the alert is not associated with the current troop surge, but that the units would replace troops currently operating in Iraq. Units flagged are: 39th Infantry Brigade Combat Team, Little Rock, Ark.; 45th Infantry Brigade, Oklahoma City, Okla.; 76th Infantry Brigade Combat Team, Indianapolis, Ind.; and 37th Infantry Brigade Combat Team, Columbus, Ohio.