The Biden Administration confirmed the Russian military used a highly secretive hypersonic missile that can travel at around five times the speed of sound at least once in Ukraine, but the question remains, why?

As USA Today reports, Biden said at a roundtable of American corporate CEOs the Russians used the missile “because it’s the only thing that they can get through” Ukrainian defenses.  He also commented that the missile is “almost impossible to stop.”

The missiles, which some claim can’t be picked up by radar, also maneuver around threats, another survival technique besides its high speed.  A video of a hypersonic missile attack on a reported Ukrainian arms cache was taken by an unmanned Russian drone.  The video showed the missile striking the structure and exploding, but no secondary explosions occurred, leading to questions about the authenticity of the video.

The video raises other questions:  if Ukrainian air defenses are so frightening to Russian forces that they are using cutting edge technology, how did a relatively stupid unmanned drone get to the target and linger over the attack site?

Military analysts have speculated that Russia wanted to test the technology, which was used in one attack in Syria in the late 2010s.  One other reported attack in Ukraine claimed to have hit a fuel depot, but witness again said they did not hear secondary explosions which one would expect, perhaps a failure of the technology.

One other possibility is that Russia is running low on its more conventional weapons, including surface-to-surface missiles and airborne munitions, making the deployment of the expensive missile a necessity.