; (2) the designation of new units of special airspace over the wilderness areas; or (3) the use or establishment of military flight training routes over wilderness areas. (g) Horses Nothing in this Act precludes horseback riding in, or the entry of recreational saddle or pack stock into, a wilderness area— (1) in accordance with section 4(d)(5) of the Wilderness Act ( 16 U.S.C. 1133(d)(5) ); and (2) subject to any terms and conditions determined to be necessary by the Secretary. (h) Withdrawal Subject to valid existing rights, the wilderness areas are withdrawn from— (1) all forms of entry, appropriation, and disposal under the public land laws; (2) location, entry, and patent under the mining laws; and (3) disposition under all laws pertaining to mineral and geothermal leasing or mineral materials. (i) Incorporation of acquired land and interests Any land within the boundary of a wilderness area that is acquired by the United States shall— (1) become part of the wilderness area in which the land is located; and (2) be managed in accordance with— (A) this section; (B) the Wilderness Act ( 16 U.S.C. 1131 et seq.)