While it’s certainly possible that the U.S. is responsible for the Nord Stream pipeline attacks, we should consider the risks of doing so. Quite a few people would know about it: those who personally made things go boom, those who delivered those personnel to the sites, those who coordinated and planned it all, and probably some in the SigInt community. The more people in the know, the greater the chance that something leaks. Think of all the secrets that have come out over the years. If it did come out the the U.S. was behind it, most Germans would probably despise the U.S. for a long, long time. Would that be a risk worth taking?
But the big question is Why? Neither pipeline was in operation or likely to be in operation any time soon.
it wont ever come out, they will never admit it. Biden already said in february if Russia attacks Ukraine nord stream 1 and 2 wont exist. He pulled out of Afganistan like he did for a reason. They have bigger fish to fry.