On February 15, 2019, the President signed a ” Proclamation on Declaring a National Emergency Concerning the Southern Border of the United States” and declared that this emergency requires use of the Armed Forces and, in accordance with section 301 of the National Emergencies Act (50 U.S.C. 1631), that the construction authority provided in section 2808 of title 10, United States Code, is invoked and made available, according to its terms, to the Secretary of Defense and, at the discretion of the Secretary of Defense, to the Secretaries of the military departments. The declaration requires the Defense department to ” order as many units or members of the Ready Reserve to active duty as the Secretary concerned, in the Secretary’s discretion, determines to be appropriate to assist and support the activities of the Secretary of Homeland Security at the southern border.”  In addition, it requires the Secretary of Defense, the Secretary of the Interior, the Secretary of Homeland Security, and, subject to the discretion of the Secretary of Defense, the Secretaries of the military departments, to “take all appropriate actions, consistent with applicable law, to use or support the use of the authorities herein invoked, including, if necessary, the transfer and acceptance of jurisdiction over border lands.”