“How America took out the Nord Stream pipeline”

There are a lot of details presented so it seems further investigation is warranted. As far as "Why American would want to take out the Nordstream pipeline", there's been an ongoing desire to get Europe to buy US LNG tanker gas to meet domestic energy demand, instead of Russian pipeline gas, and blowing up the pipeline is a step in that direction.

Of course, the optimal solution for Europe would have been to start massive renewable infrastructure development over a decade ago, then they'd be on their way to not needing any gas imports, instead of having their domestic economy held hostage like this. The rest of the world would be wise to think in these terms - fundamental necessities like energy should not be subject to the random fluctuations of global supply chains due to wars, pandemics, etc.

It's very reckless behavior if true, essentially an act of war. I can't imagine Washington politicians responding with calm deliberation if someone was blowing up US LNG tankers, for comparison.

The story does sound a little strange, but who knows? I'd have suspected the explosives were planted by underwater rover / submarine but maybe human divers are less detectable.