The conversation between human and AI assistant.
What is the operation cost of flying an SR-71 compared with U-2?
Wow, that's a significant difference. Do you know why the SR-71 was retired if it was such an advanced aircraft?
There were a few reasons for its retirement, including the high cost of operation and the development of more advanced spy satellite technology. The SR-71 also faced increasing threats from anti-aircraft missiles and the advancement of radar technology.