In this story, we dive in deep, going point by point throughout the flight path of a hypersonic boost-glide weapon and comparing the UCS analysis with its critiques. In essence, the critics argue the Union of Concerned Scientists got something wrong at every step of their analysis, from the technical details to the strategic implications. DARPA’s Project Falcon hypersonic testbed, HTV-2 UCS based their model on decade-old flight tests of an experimental DARPA design, HTV-2, which never completed a full flight test and is very different from the newer hypersonics weapons now in development. UCS graded the model on two key metrics, flight time and detectability. They concluded the hypersonic weapon would reach the US from Russia, a 5,000 mile flight, only five minutes faster than a traditional ICBM, and it could be readily detected en route by existing early-warning satellites. But they didn’t refute the larger reason America’s adversaries are pursuing hypersonics: It’s not their raw speed, but the fact that they’re much more maneuverable than ballistic missiles, allowing them to evade existing missile defenses – which the UCS study acknowledges hypersonics can do.