US had the clearest motive of all since destroying the pipelines meant not only that they could increase their control of the gas market and as you said, secure transshipment through Ukraine and Poland, but by doing so they also eliminated any possibility or pretense of Germany and Russia resuming their economic collaboration. The US had motives and plans to blow up Nordstream well before it happened. Biden said as such in Feb 2022 before Russia's SMO/invasion even began.

The bombing also forced Germany and the EU to deepen their dependency on the US and severely damaged German industry. Any benefits that accrued to Poland and Ukraine also accrued to the US. Also, US naval vessels were operating in the immediate area of the bombing, and were conducting underwater "training" exercises in the week leading up to the bombing. The US had the motive, means, and expertise to pull off the bombing. It should be obvious the USA did it.

[–] harcesz@szmer.info 1 points 1 week ago

https://archive.is/H3WXJ

A Ukrainian operative based in Poland suspected of the attack disappeared just before Polish services got to visit his place. Wouldent be surprised if they waited for him to pack; Poland was doing everything it could from Nordstreams being built.

to deepen their dependency

Temp situation, and would be short sighted as a strategy. UE has big gas resources of it's own (Norway, Ireland, "neighboring UK"). A few countries like Karat or Armenia (if I recall correctly) are looking to export gas to EU as well. Which was, according to a Russian general, the reason for their involvement in Syria. And still - EU is very actively working on shifting out all fossil fuels. Diplomatic risks for US outwaight possible benefits.

severely damaged German industry

Russia cut deliveries before the pipeline were blown up. Also the EU did not stop buying Russian gas, it capped the price. The thoughput of the currently operational pipes is enought as well, but doesent allow to blackmail Ukraine or Poland. And finally Ukraine is shutting down them, to further demolish Russian profits.

US naval vessels were operating in the immediate area of the bombing, and were conducting underwater “training” exercises in the week leading up to the bombing.

Source?