Earlier quoted context omitted.
> What I find particularly odd is that this entire thing appears to be based on a single, unnamed source "with direct knowledge of the operational planning". Why is that weird? Assuming this is true, there would be rather many people with such knowledge. One of them may feel the need to talk. Would you expect such a source to be named? Also, I find it a lot easier to imagine why the US would want to do this, than why…
You can easily imagine any of the Baltic states, Poland, Ukraine (with some local help) or even Finland, Swede or Norway doing the deed. Or, since the pipelines are well known and not difficult to reach, basically everyone with access to explosives, a boat a divers with explosives skills. None of which is particularly hard to come by.
No, one cannot easily imagine long-term neutral countries interfering in a foreign war like this.