I’d probably laugh.
I read the NY Times report on Friday, March 8, and what they say is that the missile is hypersonic. I now no longer have the paper but hypersonic is supposed to be 20 times faster than supersonic, so that is why Putin claimed nothing could catch it, I guess.
Amir also seemed just a bit tongue-in-cheek when he was talking about this, possibly a bit mocking? The Times reported speculation that there was a bit of faking going on. A lot of it is campaigning for the election. Cum grano salis, in other words. The audience at the speech seemed bored to death.