Subject to valid existing rights and Native selection rights under the Alaska Native Claims Settlement Act [
43 U.S.C.
1601 et seq.], the State, at its option, may file future selection applications and amendments thereto, pursuant to section 6(a) or (b) of the Alaska Statehood Act or subsection (b) of this section, for lands which are not, on the date of filing of such applications, available within the meaning of section 6(a) or (b) of the Alaska Statehood Act, other than lands within any conservation system unit or the National Petroleum Reserve—Alaska. Each such selection application, if otherwise valid, shall become an effective selection without further action by the State upon the date the lands included in such application become available within the meaning of subsection (a) or (b) of section
6 regardless of whether such date occurs before or after expiration of the State’s land selection rights. Selection applications heretofore filed by the State may be refiled so as to become subject to the provisions of this subsection; except that no such refiling shall prejudice any claim of validity which may be asserted regarding the original filing of such application. Nothing contained in this subsection shall be construed to prevent the United States from transferring a Federal reservation or appropriation from one Federal agency to another Federal agency for the use and benefit of the Federal Government.