There's a lot of circumstantial evidence now, building a case for means, opportunity, and motive for the US doing it, but still nothing except a weak imo motive for why Russia would have done it.it remains a conspiracy until facts are presented.
But if you're okay with this if the US did it anyway, why continue to debate it?
(By the way, the methane emission must be a necessary "unintended consequence" in your view then, too... ?)