If it was a state level actor they probably has some level of US support. Many reasons the US would want nordstream taken out, but might be unwilling to do it themselves. Enlisting someone like Poland would make sense.

And what would these many reasons be?

That's an interesting possibility I hadn't thought of. Can a faction really blow up an undersea pipeline in three places at once, though?

What I had in mind by factions is more that Russia is not a monolith. There are many different interests and groups who might be pushing in various directions. Such “factions” wouldn’t be executing something like this entirely on their own though. I’m imagining something more like them pushing through a plan like this within the Russian Navy on the Baltic and then maybe getting a green light from the top to execute.

This is at least my own understanding of Putin’s Russia - Putin only explains who the enemy is and what the Pravda is. Stakeholders vying for power in his orbit then respond by bringing forward complete solutions. He can then reward the ones he likes and punish for the ones that he doesn’t. This gives him a layer of insulation from responsibility. No one can ever say for certain that he ordered the execution of this journalist or was involved in that war-zone hospital bombing. He only has to integrate such events as they happen and refocus attention on who the enemy is. Those factions vying for his attention are also probably sabotaging each other all the time as well.

Anyways, with the conscription rolling ahead in full force and the Russian media proclaiming that enormous losses in Ukraine are due to NATO help; I think there are powerful factions within the Russian system who are pushing for a return to a healthy EU relationship with gas flowing and access to Western tech. And then there are other factions who would prefer the war to continue to escalate. Nothing quite shuts up the former group like the destruction of critical infrastructure needed to revert to the previous status quo.

I don't know. It would depend on the depth, but not even that necessarily. Now those pipes are no thin drinking straw, but think of what a bundle of fragmenting hand grenades could do. Packed watertight, with ballast, if need be. Downed from some trawler, yacht, whatever with good sonar to see where exactly, combined with with some contraption, maybe mechanical timer and CO2-cartridge blowing up a balloon which is pulling their pins. Or something more professional, which some rogue Spetsnaz surely would have access to?

Same delivery method, no divers needed. Could be almost anyone.

(shrug)

If that fraction is FSB management, why not?

Rumor is, there is enormous pressure on Putin to cede power to Patrushev son.

This may be part if a plan to force him into quitting

I can't help but recall that Igor Strelkov - the guy who, by his own admission, "started the war" (back in 2014, by occupying Slavyansk and Kramatorsk) - is ex-FSB, and ostensibly still very well connected there. And he is very much a hardliner wrt continuing the war, even if it means taking on NATO.

Patrushev is worse than Putin. It was possibly him who talked Putin into starting this war.

Not sure about it. There was a video of the Russian Security Council days before the war when Patrushev looked lost and uninformed. See http://www.kremlin.ru/events/security-council/67825/videos around 1:32