 The Navy was directed to participate in the Tactical Fighter Experimental (TFX) program with the U.S. Air Force by Secretary of Defense Robert McNamara.McNamara wanted "joint" solutions to service aircraft needs to reduce development costs and had already directed the Air Force to buy the F-4 Phantom II, which was developed for the Navy and Marine Corps.The Navy strenuously opposed the TFX as it feared compromises necessary for the Air Force's need for a low-level attack aircraft would adversely impact the aircraft's performance as a fighter.