and timing resiliency, modifications, and improvements program The Under Secretary of Defense for Acquisition and Sustainment shall treat the Positioning, Navigation, and Timing Resiliency, Modifications, and Improvements program of the Air Force (Program Element 0604201F) as an acquisition category 1D program, and the authority to manage such program may not be delegated. 1686. Actions to address serious deficiencies in electronic protection of systems that operate in the radio frequency spectrum (a) In general The Secretary of Defense shall— (1) establish requirements for and assign sufficient priority to ensuring electronic protection of military sensor, navigation, and communications systems and subsystems against jamming, spoofing, and unintended interference from military systems of the United States and foreign adversaries