By destroying the pipeline the US ensures that their “allies” (some may call them vassals) will toe the line. After all, those who were dependent on Russia are now dependent on the US.
Those with independent minds won’t suspend reason just because “Mikeb85” said it twice on hackernews.
It makes no sense for Russia to destroy the only carrot it has for Europe.
While it makes perfect sense for the US to do this.
The US position and and influence over Europe strengthens while the opposite holds for Russia.
So who do you think did it?