Vermont's Air National Guard has roots as the fifth guard unit in the United States, federally recognized in August of 1947, a month after President Harry S. Truman signed the National Security Act of 1947 which officially separated the U.S. Air Force from the Army. In 2019, the 158th Fighter Wing made history as the first Air National Guard unit to receive the F-35 Lightning IIs, and will be the second operational F-35 wing in the U.S. Air Force, scheduled to receive a total of 20 aircraft by the end of 2020.