Yes. They were not an ally until after the war started. You don't get to say "nah we don't need you" and then rely on billions of dollars after the fact, and then join the pact and reap the official benefits once the going gets bad.
If the current world order is reconfigured, America has the most to lose.
I know that no world order is forever, the US has a vested interest in the stability of the current world order and keep it as long as possible.