Because it is part of Russia's strategy to drive European energy prices higher and by forcing a hard winter to bully their way to negotiations in Ukraine.
Europe already made it clear it won't go back to Russian energy so the pipelines aren't needed anymore. This also explains why nobody started with any repairs.
For your insinuation that the US did it, there doesn't seem to be any evidence or motive. And if anybody wanted to really disrupt any Gas flow they would have needed to blow up all 4 pipes. Yet only 3 were destroyed.
Also it would have been much too dangerous for any NATO member to engage with a military action against Russian property.
It is most likely that Russia had already installed bombs during construction and just had to pull a trigger.
Europe already made it clear it won't go back to Russian energy so the pipelines aren't needed anymore. This also explains why nobody started with any repairs.
For your insinuation that the US did it, there doesn't seem to be any evidence or motive. And if anybody wanted to really disrupt any Gas flow they would have needed to blow up all 4 pipes. Yet only 3 were destroyed.
Also it would have been much too dangerous for any NATO member to engage with a military action against Russian property.
It is most likely that Russia had already installed bombs during construction and just had to pull a trigger.