In the Rainbow 5 plan, it states: "Since Germany is the predominant member of the Axis Powers the Atlantic and European area is considered to be the decisive theatre. The principal United States Military effort will be exerted in that theatre and operations of United States forces in other theatres will be conducted in such a manner as to facilitate that effort." The United States believed that Germany was the stronger of the two and decided to get rid of them first no matter what. They decided that even if the Japanese should enter the war, Germany was still their main goal. "If Japan does enter the war, the Military strategy in the Far East will be defensive." As we all know, Japan entered the war and the US stuck to the plan.

Two of the important objectives outlined in the Rainbow 5 plan were the security of the United Kingdom and the security of the sea communications. These were both threatened by Germany. The UK was in danger of being invaded by the Germans and U-Boats were sinking American ships. That gave the Americans two more reasons to focus on Germany first.