Try as they did, and they did and still try, not the Russkies, the ChiCOMS, the NKs nor anyone else been able to replicate the SR-71
I interviewed a Lt. Colonel who had been assigned to the SR-71 back in the 70s. Remarkably, he had been a Enlisted Crew Chief on a B-25 and was shot down over North Korea.
He survived a NK prison camp, returned to the USAF and was chosen for pilot training. He made the grade and was married and received his 2nd Lt. bars on the same day.
Great story...