What possible gain is there for Russia to blow up the off-ramp to the gas sanctions?

I didn't say Russia did it. I mean it probably did but Germany isn't off the table. Unlike the US Germany actually has the stealth subs to pull it off undetected, but all in all Russia is still the more likely option I'd say. Of course, the presence of ships in that area etc. is only circumstantial evidence.

And in your analysis you're making a crucial mistake, a mistake I myself made directly before the invasion when Russian soldiers were getting itchy underwear on Ukraine's border because I thought if they're going to attack, they'd already have done it: You assume Russia is a rational actor. Or, maybe better put, that it considers the same things as rational as you do.

Blowing up NS2 from Russia's side could have the motive of a) knowing or suspecting that you don't need it any more -- though it also wouldn't be terribly hard to repair which people are constantly overlooking and b) to provide an excuse to stop deliveries. Russia was playing around back at that time with NS1 maintenance and turbines being needed which were stuck in the sanctions regime etc, allthewhile Germany was filling its gas storage and nationalising Russian gas assets on German soil. They might've thought that they need to disable NS2 so Germany wouldn't say "well if NS1 doesn't work why don't we use NS2".

As to the US threats: What was probably meant was sanctions. It's true that the US has levers it can pull to force such an issue. Those would come at a cost to the US itself but they're there and can be pulled if the cost is deemed acceptable.

And btw one thing is for sure: Germany will never again buy any (noticable) amount of Russian gas. Even if they retreat to their own borders tomorrow that ship has sailed, Germany is in full swing to replace all that fossil infrastructure with ammonia and hydrogen. NS2 is dead no matter whether it's operational or not.

Oh another thing is for sure: Ukraine is way more important to Russia, or maybe better put Putin, than some gas pipeline. Pretty much the moment Germany changed laws to legalise sending weapons into crisis territories, i.e. Ukraine, Russia knew where Germany stood, and will continue to stand. We don't tend to flop easily and they know it. As such it also might simply have been Putin being stroppy, expecting Germany really to go for that Duginesque^1^ division of Europe between great powers things, with Germany taking a forceful lead in Europe. He did later on comment that "siding with Ukraine was Germany's mistake of the millennium" or something to that effect. So much for Putin's rationality, he's living in a completely different world than us, thinking state relations and decisions work on fundamentally different principles than they actually do.

^1^ not really, Dugin never came up with that stuff he's not a theorist he just rehashes nationalist bullshit those theories actually date back to the German Empire trolling the Russians to bait them it's a long story.

They threatened to blow it up for years without end and now you gotta buy natural gas from them at a premium.

What. We're not buying US gas, not in any noticeable amount, that is. First of all usage was cut drastically (the likes of BASF could switch to other energy sources), most gas we still consume comes from Norway, LNG overall is only a tiny portion and of that most is Qatar.

If the US really did it then Germany is holding tight right now for Ukraine's sake and there's going to be hell to pay after the war.

Oh, and you gotta cut your welfare system and spend it all on american weapons too.

What. The only reason any amount of US hardware is on our shopping list is because Eurofighter GmbH doesn't want to give the US access to data they'd need to certify US nukes for the Typhoon because industrial espionage. F-35s are already certified, available off the shelf, and our Tornado fleet really needs replacement but really, it's just for the nukes: The EWAR Tornados are getting replaced not by F-35s, but more, freshly designed, Eurofighters. Down the line there's going to be FCAS and likely French instead of US nukes. Now it's not that I'm saying that France would be less prone to industrial espionage than the US, in fact they're notorious for it, but they already have all that data through Airbus anyway.

Poland is going on a shopping spree for quite a lot of American hardware, but that's another topic, also, focussed very much on airframes. Tanks and artillery are onshored South Korean systems (which are onshored German systems). France will never buy American because strategic autonomy, in fact they were right-out insulted when hearing Germany is going to buy F35s, but seem to have cooled down seeing that it's a stop-gap solution.