WesWorld

Quoted from "The Rock Doctor"

America and the UK were intended to isolationist Great Powers, activated only if the mods needed an in-game mechanism to keep a player in line.

We ended up with twenty countries capable of building battleships because we had twenty guys who wanted to design battleships. Economic rationality had little to do with it.

That sums it up fairly well, there's also an interesting yarn we could tell you about why there was so many alliances set up early on.....

Alliances is an important point.
The USA is a member of NATO, although largely a sleeping alliance these days and rather overtaken by the GA, its gives the USA much stronger support should Iberia go nutty on its doorstep and to a certain extent a backdrop for the Pacific too, though SAER would be of more use to contain Japan.