At that point any response on Russia's part would have just played in to NATO's war mongering. If it could be shown to be Russian action then you'd have the "mystery" of the nordstream 2 but look over hear Putler attacked X! If it couldn't be shown to be russian action then as far as the public is concerned that's just two mysteries, and the US just proved to Russia and the EU that it's more than willing to destroy it's own allies and take direct unprovoked attacks against a nuclear power just for chump change so you can't really out-crazy that.
At that point any response on Russia's part would have just played in to NATO's war mongering. If it could be shown to be Russian action then you'd have the "mystery" of the nordstream 2 but look over hear Putler attacked X! If it couldn't be shown to be russian action then as far as the public is concerned that's just two mysteries, and the US just proved to Russia and the EU that it's more than willing to destroy it's own allies and take direct unprovoked attacks against a nuclear power just for chump change so you can't really out-crazy that.