If the Secretary of the Army dies, resigns, is removed from office, is absent, or is disabled, the person who is highest on the following list, and who is not absent or disabled, shall perform the duties of the Secretary until the President, under section 3347 of title 5, directs another person to perform those duties or until the absence or disability ceases:
((1)) The Under Secretary of the Army.
((2)) The Assistant Secretaries of the Army, in the order prescribed by the Secretary of the Army and approved by the Secretary of Defense.
((3)) The General Counsel of the Department of the Army.
((4)) The Chief of Staff.