In the immediate aftermath of the attack someone on Twitter pointed out a US navy warship was parked at the blast site in the days preceding the blast. I looked up a marine ship tracking website I had used on occasion and quickly discovered that yes, the USS Kearsage was parked above the attack site up until about 48 hours before the blasts went off. The Kearsage is an amphibious assault ship that has the kind of deep well, equipment and crew used for SEAL teams to conduct just this kind of attack. And I found news reports that it was doing "training" in just such activities in the Baltic in the weeks prior to the attack.
So it's nice to have the confirmation from that Hersh fellow that the US is responsible for the Nordstream attacks, but it was already obvious to anyone willing to do a little sleuthing of their own. These pathetic propaganda efforts to claim Russia cut off their own income and diplomatic leverage by destroying the pipelines remain utterly stupid and senseless.