"Or, how would Orwell have responded to the US
expansionism today?"

I do not know how Orwell would have thought about expansionism, but I
know how I feel. Expansionism at any time and place is the result of
excess stored energy or energy greater than the immediate
surroundings. America just happens to be the country with the most
energy and is now in the process of diffusing and spreading its
energy. I think this is some kind of law of matter that more
concentrated substances will always flow to a state of less
concentration. America today is like the blue dye added to a cup of
water, a potent blue that will eventually become a dilluted blue.
This law of energy and matter moving from a greater concentration to a
lesser concentration along paths of least resistance can also be seen
in chess games. The parts of the position with more concentrated,
energetic material will flow into areas of the board that offer least
resistence. Of course the best players, Botvinnik included, knew how
to handle opponents who offered the greatest resistance. Resistance
like anything else that happens on the chess board can only be done by
making legal moves or by letting material stand on squares (refraining
from making legal moves).
Thanks