The Flying Tigers (Americans flying American planes for Nationalist China) were already fighting the Japanese for years at that point (while our government legally blocked Americans from fighting in Spain), and we had an embargo on Japan while arming Britain; we were already in the war.
And we were actively bombing uboats on our side of the Atlantic to protect arms convoys to England. It was only a formality that we ‘weren’t’ at war.
Thank God we didn't fight for the so called Loyalists in Spain. Those anti Franco Communist were disgusting human beings who took great pleasure in searching out, torturing and killing Catholic priest and defiling, raping and then murdering nuns. And yes Franco was no walk in the park either.