[atoav]

I asked myself the same question, but one theory I sort of found imaginable was that this was about internal political stability and signposting.

To get the part of Russias elite on board who just wanted to go back to selling gas/oil to Europe a sacrifice had to be made.

I mean not that I find that very likely, but it is an explaination

[pclmulqdq]

I think this is the most plausible theory that explains Russian backing. An alternative theory is that this was an accident from them trying to fix hydrate plugs in the pipes, and doing it wrong. Another possibility is that Russian popular support for the war could be flagging, and Putin was trying to drum up unity.

However, Putin has not been shy about simply seizing assets using the Russian legal system, so destroying an important strategic asset to keep the oligarchs in line seems like an extreme move. The popular support battle, for Putin, already seems to be lost, and it's unclear why blowing up a pipeline would help.

If he did blow up the pipeline, whether it was an accident or a power play, blaming the US (which he is doing) makes a lot of sense.

The elephant in the room is that there is a great reason why the US (or Ukraine, if they had the operational capability, or Turkey or France, for that matter) would blow up the pipeline: it closes off Europe's options to buy oil from Russia this coming winter, which, in turn, ensures that they have no reason not to support the war. However, if they did blow up the pipeline, they certainly couldn't admit it, and they would need to find a scapegoat, and the best scapegoat is the country they want Europe to be angry at: Russia. The US has an additional possible motivation: it opens the path to selling LNG to the EU.

So here we are. Russia blames the US, the US and NATO blame Russia, and nobody has claimed responsibility. This is consistent with either truth of who actually did it. Eventually, we may know the truth about what happened. We certainly don't know today.