> Russia has invaded Ukraine and encountered NATO materiel paid for by NATO money and NATO trained soldiers using NATO intelligence to kill Russian troops and generals.

They did not. It took 8 years, until the renewed invasion, before any meaningful supplies began arriving in Ukraine. Western leaders had to be shown mass graves before they were willing to provide heavy equipment.

> Well, I'm not sure what their strategists are thinking but my take is the US demonstrated that peace was not an option and they are going to keep increasing the temperature until Russia's red lines get crossed. With that context, it makes sense to be on the side that will win the upcoming conflict(s).

Sweden had been neutral since 1814: it went through both world wars and the Cold War without choosing sides. If we accept the premise that Russia is reacting to NATO and that the Americans are responsible for everything, then why would the events in Ukraine drastically change the outlook for Sweden?

You can't give a plausible explanation, because there is none, because the situation has nothing to do with NATO or the Americans.

Russia has begun violating agreements that even the USSR adhered to, such as the 1975 Helsinki Accords (in short: no violent territorial changes in Europe)[1]. For a long time, Sweden and Finland believed that they could avoid Russian aggression through careful diplomacy, and stand against Russia independently when required, but the war against Ukraine was unprovoked and far beyond Nordic military capabilities, dashing both hopes.

So now you have two key factors:

1. Increasingly hostile neighbour.

2. Insufficient military strength.

How do you respond?

Nordic military and political leaders concluded that tighter international cooperation is the only way to survive this situation. For example, a country with 5 or 10 million people can't afford air defense network that could protect their people from such drone and cruise missile attacks like Ukraine is experiencing; they need external help.

Nordic countries have a fair bit of history with Russia too and can see through the bullshit that many westerners don't immediately recognize. You know where "Molotov cocktail" came from? In 1939, Russians staged the shelling of Mainila[2], claiming that Finns were responsible. Four days later, Russians launched unprovoked war against Finland. As Russian planes were bombing Helsinki, Russian propaganda kept blasting that the planes were delivering food to starving Finns. Molotov cocktail was the hot drink Finns devised to go with the "bread baskets" that bombers were dropping.

And like the fake republics of Luhansk and Donetsk that Russians set up in Ukraine, Russians had established the Finnish Democratic Republic[3], ready to take over the entire Finland as soon as Russian tanks rolled over it. But Finns put up a stiff resistance and kept their independence.

All that is still in living memory, people still have grandparents alive to tell how it was back then. The Russian invasion of Ukraine, using the same methods, leaves no room for doubt for what's really going on and who's responsible.

[1] https://en.wikipedia.org/wiki/Helsinki_Accords

[2] https://en.wikipedia.org/wiki/Shelling_of_Mainila

[3] https://en.wikipedia.org/wiki/Finnish_Democratic_Republic