I always thought it's more likely that somebody from the West did it, since from my perspective it helped West and not Russia. But what's confusing me is the rather muted reaction from Russia. If it wasn't them and if they believed it's the West, why are they so silent about it?
It's just strange they keep largely silent on this, even though it seems like a golden opportunity. Why are they not attacking German society with "Americans are trying to freeze you, they blew up the pipes"?