John Mearsheimer and Stephen Walt first came out of academic obscurity with their strong opposition to the Bush war in Iraq. Their to some extent sensible and in retrospect correct arguments failed to influence American decisions. The reasons, which their limited theoretical comprehension of politics has no means to fathom, have to do with the fact that political decisions are not made in an intellectual and rational vacuum. Faced with failure of their arguments, they responded in an old-fashioned way: blaming the Jews. Although they had not previously exhibited any signs of the disease, their anti-semitic screed gained them widespread credibility among the hard left, not so much in the US as abroad.
It has just now come to my attention that they have completed their move to full-fledged members of the fifth column by supporting Putin's invasion of the Ukraine, as well as a number of other tyrannies. One should not put it beneath a Harvard professor's dignity to have opinions shaped under the influence of lucrative grants from the neo-Tchekist regime. They would be joining, among others, the Le Pen supporters in France, most of which had in any case previously being associated with Moscow gold anyway. However I think it more likely that the transition through the extreme left into the extreme right came naturally and of their own accord, as a reaction to their own intellectual failures.