an offensive war is much harder than a defensive one.
Agreed
America would have to maintain gigantic transoceanic supply lines.
True, but America already maintains these, even without ongoing conflicts. If they moved carrier groups from the Pacific, even easier.
America has a low tolerance for casualties, especially in foreign lands.
I don’t think so. They seem pretty okay with casualties in every war since Vietnam. Compounded with the likelihood most casualties wouldn’t be extracted to the US until the end of a major conflict, it gets even easier.
Such an invasion would cause huge social unrest at home. Presumably such an invasion would be instigated by trump who would then be compelled to deploy the military at home as well.
Sadly, this could legally work. The USA military is beholden to the president over anyone else. So long as an action isn’t unconstitutional, it’s legal if it comes from POTUS.