Honestly, the timing doesn't make sense. I'd maybe the US blowing the pipelines a year ago when it looked as though NS2 might conceivably go online, but given how frosty relationships are right now between the EU and Russia, and given the scramble to wean Europe off Russian gas-dependency already is in progress, there just doesn't appear to be much of a point, not in the short term and not in the long term.
Why would Russia invade and annex Ukraine? The answer can be stupid people making stupid decisions, don't assume everything done by a nation-state is logical.
> Russia has good geopolitical reasons for invading Ukraine.
They had good reasons to maybe want to dominate their neighbor. What good reasons were there to risk everything over an all out land war, and what reasons remain for continuing a fight they are losing ?
Then again, Russia might not have the monopoly on stupidity.