Final answer:
The U.S. Air Force is constitutionally justified through the Necessary and Proper Clause, allowing Congress to adapt its military forces, including the creation of an Air Force, which is implied within its powers to raise, support, and regulate the military.
Step-by-step explanation:
The question revolves around how the U.S. Air Force is constitutionally justified, given that Article I, Section 8 of the U.S. Constitution explicitly grants Congress the power to raise and support armies and maintain a navy, without mentioning an air force. The existence of the U.S. Air Force is constitutionally supported by the use of the Necessary and Proper Clause found at the end of Section 8, which grants Congress the authority to make all laws which shall be necessary and proper for executing its vested powers. This broad interpretation allows for the adaptation of military forces to include the Air Force. Congress's power to declare war, raise and support armies, provide for and maintain a navy, and make rules for the government and regulation of the land and naval forces implicitly allows for the creation of an air force to adapt to changes in warfare and technology.