The 138th Infantry Regiment is an infantry regiment of the United States Army and the Missouri National Guard headquartered in Kansas City, Missouri.

The 39th Infantry Brigade Combat Team, also officially known as The Arkansas Brigade, is an infantry brigade combat team of the Army National Guard composed of personnel from the U.S. states of Arkansas, Missouri, and Nebraska. The unit is the largest Army National Guard command in Arkansas and is headquartered at the Camp Robinson Maneuver Training Center. It was ordered into federal service in 2003 in support of Operation Iraqi Freedom II. The 39th was attached to the 1st Cavalry Division and served in and around Baghdad for a year, returning to the United States in March 2005.