The powers of the national government are listed (enumerated) in Article I of the Constitution. They are designed primarily to allow the national government to declare war, regulate interstate commerce, issue currency, and establish an army and navy. Implied powers allow the national government a degree of flexibility to enable it to respond to changing circumstances; the necessary and proper clause, also called the elastic clause, gives Congress the power to make all laws that are necessary and proper to the execution of its enumerated powers. All powers not specifically granted to the national government and not specifically denied the states are reserved for the states by the Tenth Amendment, which was meant to guard the states against encroachment by the national government.