At that point, it was too late. WWII was caused by Woodrow Wilson. He lied to USA voters, with the campaign slogan "He kept us out of war!" that was widely celebrated until a month after his re-inauguration when he rushed us into war. With USA saving their asses, UK and France had no reason to negotiate with Germany in good faith. If we had left them to suffer the consequences of their poor decisions, they would have found a way to live in peace with the Germans.