Some state actor is very likely to have been involved. However there are benefits and drawbacks for almost anyone who could have done it. That it's "obvious" t

Some state actor is very likely to have been involved. However there are benefits and drawbacks for almost anyone who could have done it. That it's "obvious" the US did it doesn't mean the US did it. Russian propaganda thrives in uncertainty and the US being the foregone conclusion certainly reinforces anti-US sentiments in Europe, which ultimately harm the US for the benefit of Russia. We can't really deduce the motive based on the actual outcome though. It was evidently a literal conspiracy, it's just not entirely clear who was involved and who knew about it. Personally I believe that if it really was the US, Sweden and Germany were in the know. Not involving them would have sown distrust against the US in a time of crisis (tho the US has a history of performing acts of aggression against its allies, cf. the Diplomatic Cables revelations and Snowden leaks). But this also means Germany willingly handicapped itself, not that this makes it less likely.