Germany claims that it could stop construction of the new gas pipeline to Russia, or shut off its use, as punishment for Russian aggression.

I am skeptical of the claim. Once the pipeline is in use, EU countries would become dependent on it, and their pressure to keep it running would be even harder to resist then, than their pressure to finish it is now.

The EU should cancel this pipeline and adopt stronger measures to decarbonize. It needs to do that anyway.