The SR-71's actual top speed was classified, and the 'official' top speed was faster than anything else in production.
At several points growing up someone would come up with a new plane that encroached on the SR-71's speed record. Then a couple weeks later there would be an announcement about the SR-71 setting a new top speed.
I suspect someone in Intelligence had to decide that being officially the fastest was important, but exactly how fast being a secret made the plane and pilot a little bit safer. So they had to nudge the fiction a little bit closer to the truth any time there was a pretender. Or, manufacturing improvements nudged the maximum safe speed up over time, and they only bothered updating the public about this when a dick measuring contest was held in their honor. Or maybe both.
At several points growing up someone would come up with a new plane that encroached on the SR-71's speed record. Then a couple weeks later there would be an announcement about the SR-71 setting a new top speed.
I suspect someone in Intelligence had to decide that being officially the fastest was important, but exactly how fast being a secret made the plane and pilot a little bit safer. So they had to nudge the fiction a little bit closer to the truth any time there was a pretender. Or, manufacturing improvements nudged the maximum safe speed up over time, and they only bothered updating the public about this when a dick measuring contest was held in their honor. Or maybe both.