Were there Soviet contemporaries to the U-2, X-15 and SR71?

It all came full circle. The MIG 25 was built in response to fear of the XB-70.

This doesn’t make a bit of sense. The SR-71, and its predecessor, the A-12 ‘Oxcart’, were built for a specific purpose; to overfly the Soviet Union at speeds and altitudes exceeding any credible intercept capability. (It was originally intended to fly so fast that it would be ‘stealthy’ to early “blip-scan” radar, although with better analog and later digital filtering capability this anti-radar capability was negated.)

The SR-71 was retired because it was incredibly expensive to operate for the capabilities it offered, and for which the kind of high-and-slow reconnaissance missions required today can be performed by the U-2R and U-2S or by unmanned aerial surveillance vehicles. In the future, stealthy reconnaissance UAVs capable of both high speed transit and low speed dwell at a variety of altitudes will provide those capabilities.

The X-15 was always an experimental rocket powered vehicle designed to research aspects of high altitude and high speed flight. It was never used for any operational purpose.

As noted, the Soviet Union didn’t have direct contemporaries to these vehicles, but they did have some interesting vehicles and prototypes of their own for both high speed transit and high altitude/space research, including the interesting MiG-105 ‘Spiral 50/50’ vehicle filling somewhat the same niche as the proposed X-20 ‘Dyna-Soar’, albeit with a different flight mode (two stage aircraft-lofted orbital lifting body versus the Dyna-Soar’s rocket ascent profile on a Titan-3M), and the Tupalev Tu-123 reconnaissance drone.

Stranger

Same aircraft type (MiG-25) but two different incidents… In the early 1970s (1971 or 1972) radar operators clocked a MiG-25 (probably a Soviet reconnaissance version) over the Sinai peninsula at Mach 3.2.

Ten years later, in 1982, the Israelis shot down a Syrian MiG-25 over Lebanon using a Hawk SAM and an F-15 - since it was in a third nation’s airspace, this would normally have caused a major international incident but this was during the phase of Lebanon’s civil war when the Israelis were shooting down Syrian aircraft frequently over Lebanon, so it didn’t have that large an effect.

(Mikoyan-Gurevich MiG-25 - Wikipedia)