First, there’s no “if”, it’s a fact that can be easily verified. Second, I don’t pretend to know for a fact it was Russia. One of several reasons that I think it’s most likely is that Russia is the country involved here where one man’s irrational decisions would turn into action with virtually no checks.
Russia can close the valves on their end, and germany cannot do anything, since the EU their contractual obligations and literally promising to steal russian assets.
Destroying the pipelines doesn't benefit neither germany nor russia.
The volume has certainly been going down for a while, I'm not sure who's responsible for that. Like I would actually need to research that part. Russia can stop the pump while Europe can suspend payments. Both actions have the same effect on volume sold.
and isnt it somewhat reasonable that if we do not believe the maintenance explanation, that it MIGHT just be that they are doing it to force the germans to put the stamp on the final opening approval for nord stream 2? there is a reason nord stream 2 was created, even though nord stream 1 exists.