What Germany would lose through a symbolic war on Japan

Even a largely symbolic German declaration would rupture the Tripartite Pact. It would also interrupt Japanese supplies of scarce materials, including shipments through European ports. The scenario offers no comparable gain in access to American resources. Roosevelt could point to Germany's lack of practical assistance against Japan when responding to the gesture. The follow-up therefore adds material and diplomatic costs to the earlier problem of Germany's inability to conduct the campaign.