This day in aviation history, August 7th, marks an interesting highlight with the first test flight of the YF-12A fighter aircraft based on the SR-71. The SR-71 speed and altitude records were legendary and the fighter concept was designed to counter the former threat of the Mig 25 supersonic fighter. The linked article has more information but this would have been a great balloon killer for high altitude balloons like the recent air intercept of the Chinese Spy balloon. That intercept tested the altitude limits of our current fighters. Link to an article on that here.