The National Guard is among the seven reserve components of the armed forces of the U.S. There are two components: the Army National Guard and the Air National Guard. The National Guard is under the service of state government. It was erected following the Militia Act of 1903, as a method for curbing federal sovereignty and protecting the interests of individual U.S. state governments. However, when called to federal duty by the President of the U.S., the National Guard must answer. The National Guard functions to preserve law and provide disaster relief in times of crisis.