An area established on non-Federal lands located within the United States or its possessions or territories for the purpose of safeguarding classified defense information or protecting Department of Defense (DOD) equipment and/or materiel. Establishment of a national defense area temporarily places such non-Federal lands under the effective control of the Department of Defense and results only from an emergency event. The senior DOD representative at the scene will define the boundary, mark it with a physical barrier, and post warning signs. The landowner’s consent and cooperation will be obtained whenever possible; however, military necessity will dictate the final decision regarding location, shape, and size of the national defense area.