>WHY would Russia tell the world?
Russia releases info on hypersonic MIRV nukes.
Either
1) they're acting strong, but are weak (possibly to counter our orbital weapon lancets?)
2) the IG report (or state Dept IG) will release that Hillary "sold", by leaving her email server poorly secured (for plausible deniability), hypersonic nuke tech to Russia as part of the U1 deal. Russia is getting ahead of it to keep the nuclear balance of power publicly even (i.e. they have the same tech as the US, because it was stolen from us thanks to HRC).
#2 also makes it so that we aren't tempted into war with them when the information comes out about how our former leaders sold us out to them.
It's a strategic move to keep the playing field level in either case, with respect to MAD, such that MAD still applies.