Unmanned Aerial Security Act or the UAS Act This bill prohibits the Department of Homeland Security (DHS) from operating, financing, or procuring unmanned aircraft systems (UAS) or UAS operating, detection, or identification systems that are manufactured in certain foreign countries or by business entities domiciled in such foreign countries. Applicable foreign countries include those identified as foreign adversaries in the intelligence community's latest annual threat assessment and other countries designated by DHS. DHS may waive the prohibition for (1) the national interest of the United States; (2) counter-UAS surrogate research, testing, development, evaluation, or training; or (3) intelligence, electronic warfare, or information warfare operations, testing, analysis, and training. An office or component of DHS may continue to operate a UAS or system in its inventory that would otherwise be prohibited until DHS grants or denies a waiver or until one year after this bill is enacted, whichever is later.