Aerial reconnaissance
In spite of the formal end to reconnaissance aircraft overflights, the U.S. remained involved in overflight attempts of its Cold War adversaries. Project Dark Gene, a CIA–Iranian program of intrusions into Soviet airspace to explore Soviet air defense systems, continued operations up to 1979. Aerial reconnaissance of mainland China continued with the Ryan Model 147 "Lightning Bug" RPVs (Remotely Piloted Vehicles); several of these drones were shot down or recovered by the Chinese during the Vietnam War era. China overflight efforts prevailed into the 1970s with proxy U-2 missions flown by Taiwanese pilots.