Sorry, I mixed him up with Scott Ritter, another favorite among apologists since he also defended Russia's annexation of Crimea and its aggression towards Ukraine. In fact, he is a regular contributor to Russian state media sources, and he was busted twice for trying to have sex with minors!

https://en.wikipedia.org/wiki/Scott_Ritter

Mearsheimer is another case alogether. He's also an apologist favorite, but not a criminal pervert. For him, it comes down to parroting the same lines Putin uses, blaming NATO for the fact that Russia invaded it. He's a cynical realpolitik type who blurs the lines between what is practical and what is ethical and legal.