US is the only country that has a clear motivation and the means for blowing up the pipeline. Biden literally said that pipeline would stop operating if Russia invaded Ukraine in a press conference. Polish MP promptly thanked the US after the pipeline was destroyed, and Nuland recently all but admitted this. German intelligence recently said they are becoming open to the idea that a western nation was responsible. Printed in an approved propaganda outlet to boot. It would require extraordinary proof to claim that US is not the responsible party here.