sentences:  It is one of the 29 original National Guard Observation Squadrons of the United States Army National Guard formed before World War II.The 121st Observation Squadron was ordered into active service on 1 September 1941 as part of the buildup of the Army Air Corps prior to the United States entry into World War II.On 24 May 1946, the United States Army Air Forces, in response to dramatic postwar military budget cuts imposed by President Harry S. Truman, allocated inactive unit designations to the National Guard Bureau for the formation of an Air Force National Guard.