What you should know about Russian hypersonic missiles used in Ukraine, and real game-charger Putin keeps for last

US President Joe Biden confirmed Monday Russia has used hypersonic missiles in its invasion of Ukraine,     .

“And if you’ll notice, (Russia has) just launched the hypersonic missile, because it’s the only thing that they can get through with absolute certainty,” Biden said. “It’s a consequential weapon … it’s almost impossible to stop it. There’s a reason they’re using it.”

But Biden’s own defense secretary have downplayed Russia’s use of its air-launched Kinzhal missiles.

“I would not see it as a game changer,” Pentagon chief Lloyd Austin told CBS’ “Face the Nation.”

And the UK Defense Ministry said the Kinzhal missile is really just an air-launched version of the Iskander short-range ballistic missile (SRBM), which Russia has used repeatedly in its invasion of Ukraine.

Analysts say hypersonic missiles which travel faster than sound are not a new war tech—unlike the glide vehicle (HGV).

An HGV is a highly maneuverable payload that can theoretically fly at hypersonic speed while adjusting course and altitude to fly under radar detection and around missile defenses.

And Russia is thought to have an HGV in its arsenal, the Avangard system, which Russian President Vladimir Putin in 2018 called “practically invulnerable” to Western air defenses.

Russia, the US, North Korea, and China are working on perfecting the HGV systems.