The Congress further declares, in accordance with our traditional military policy as expressed in the National Defense Act of 1916, as amended, that it is essential that the strength and organization of the National Guard, both Ground and Air, as an integral part of the first line defenses of this Nation, be at all times maintained and assured.
To this end, it is the intent of the Congress that whenever Congress shall determine that units and organizations are needed for the national security in excess of those of the Regular components of the Ground Forces and the Air Forces, and those in active service under this chapter, the National Guard of the United States, both Ground and Air, or such part thereof as may be necessary, together with such units of the Reserve components as are necessary for a balanced force, shall be ordered to active Federal service and continued therein so long as such necessity exists.