You're confusing pool's with individually owned miners, or specific like minded group. A pool can be 100s or 1000s of individual miners spread all around the world.

While the US as a whole is close to being half (48%), it wouldn't mean there would be a 51% attack from the US due to that if it had 51%, it would be individuals or companies, not 1 actor, or coordinated group of like minded actors.

For a real 51% attack on the network it would be too costly for it to even be feasibly worth doing so at this point. I'm not claiming that it's not possible, just that it is very unlikely at this point in time. It would require buying up a great amount of land, possibly building your own power plant and buying 100's of 1000's top tier asic miners, 2 or 3 times more than any 1 countries individually owned miners as a whole in order to be successful. Possible, but extremely unlikely.