Whenever the Secretary of the Army, Navy, or Air Force determines that it is necessary to lease any land held by the United States on or near a military installation to effectuate the purposes of this subchapter, he may lease such land upon such terms and conditions as will, in his opinion, best serve the national interest. The authority conferred by this section shall be in addition to and not in derogation of any other power or authority of the Secretary of the Army, Navy, or Air Force