including deadly fentanyl, entering the United States. The Secure Fence Act of 2006 ( Public Law 109–367 ) requires the Secretary of Homeland Security to take all actions necessary and appropriate to achieve and maintain operational control over the entire international land and maritime borders of the United States[.] . The Act defines operational control as the prevention of all unlawful entries into the United States, including entries by terrorists, other unlawful aliens, instruments of terrorism, narcotics, and other contraband. . During the Trump Administration, the Department of Homeland Security constructed approximately 450 miles of new and replacement border wall system