Russia says it's destroyed an underground weapons warehouse in western Ukraine using hypersonic ballistic missiles.
They fly at up to 10 times the speed of sound.
Its flight path is also erratic, meaning no current defence system can reliably track and intercept them.
Igor Konashenkov, from the Russian Defence Ministry confirmed the news:
"On the 18th of March, the Kenzahal Aviation Rocket System with hypersonic ballistic missiles destroyed a big underground missile arsenal with aerial ammunition of the Ukrainian forces".
