; (B) electronic warfare; or (C) information warfare operations; and (2) is required in the national interest of the United States. (c) Waiver The head of an executive agency may waive the prohibition under subsection (a) on a case-by-case basis with the approval of the Secretary of Homeland Security or the Secretary of Defense and notification to Congress. 4. Prohibition on operation of foreign commercial off-the-shelf drones and small unmanned aircraft systems (a) Prohibition (1) In general Beginning not later than 180 days after the date of the enactment of this Act, no Federal department or agency may operate a commercial off-the-shelf drone or covered unmanned aircraft system manufactured or assembled by a covered foreign entity. (2) Phase-in period for existing contracts The prohibition under paragraph (1) shall not apply, during the 1-year period beginning on the date of the enactment of this Act, to commercial off-the-shelf drones and covered unmanned aircraft systems procured through a contract entered into before the date of the enactment of this Act. (b) Exemption The Secretary of Homeland Security and the Secretary of Defense are exempt from the restriction under subsection (a) if the operation or procurement— (1) is for the purposes of training, testing, or analysis for— (A) counter-UAS surrogate intelligence; (B) electronic warfare; or (C) information warfare operations