After more thought (and Googling), not to mention the bullshit the U.S. gov't has pulled on its own people the past couple of years, I've come to the conclusion that it would NOT be out of the realm of possibility that the U.S. might've been involved. Snippet from an ABC News article yesterday:
"President Joe Biden promised on February 7 to prevent Nord Stream 2 from becoming operational if Russia invaded Ukraine. "If Russia invades,” said Biden, “then there will be no longer a Nord Stream 2. We will bring an end to it."
Reporter: "But how will you do that, exactly, since...the project is in Germany's control?"
Biden: "I promise you, we will be able to do that."
Demented Joe saying more than he should or simply arrogant political hyperbole? Makes you go hmmmmmmmmmm...