An American military investigator examining instances of the syndrome told 60 Minutes that the common link between victims of the syndrome was a “Russia nexus”.
Greg Edgreen explained: “There was some angle where they had worked against Russia, focused on Russia, and done extremely well.”
He also said the official US bar of proof to show Russian involvement had been set too high, as his country did not want to “face some very hard truths”.
Crucially, this started happening in late 2016, and reports became more widespread (including Canadian foreign ministry personnel) in 2017.
TL;DR Trump or one of his toadies decided to made the burden of proof insanely high because Trump likes Putin.