“If this Government remains in power for another year and carries on in the same measure in this direction, it will go far towards making Germany a danger to world peace for years to come.
With few exceptions, the men who are running this Government are of a mentality that you and I cannot understand. Some of them are psychopathic cases and would ordinarily be receiving treatment somewhere.”

The above quote is included in a dispatch to the State Department in 1933 from George S. Messersmith (unrelated to Wilhelm Messersmith, German engineer), American consul general stationed in Germany. Likewise, ambassador to Germany William Dodd repeatedly warned of Hitler’s Germany preparing for war.
Some historians portray these diplomats as “voices in the wilderness” who were ignored. On the contrary, the FDR administration was aware of the US caught in the current of European events and contentious affairs of state that could inevitably lead the country into another war, despite US neutrality and strong isolationist sentiment.
The bombing of Pearl Harbor surprised even Germany. Although Hitler had made an oral agreement with his Axis partner Japan that Germany would join a war against the United States, he was uncertain as to how the war would be engaged.
Japan’s attack on Pearl Harbor answered that question. On December 8, Japanese Ambassador Oshima went to German Foreign Minister von Ribbentrop to nail the Germans down on a formal declaration of war against America. Von Ribbentrop stalled for time; he knew that Germany was under no obligation to do this under the terms of the Tripartite Pact, which promised help if Japan was attacked, but not if Japan was the aggressor. Von Ribbentrop feared that the addition of another antagonist, the United States, would overwhelm the German war effort.
Hitler thought otherwise. He was convinced that the United States would soon beat him to the punch and declare war on Germany. The U.S. Navy was already attacking German U-boats, and Hitler had an undisguised contempt for anything American generally and FDR specifically. He also believed that Japan was much stronger than it was; that once it had defeated the United States, it would turn and help Germany defeat Russia. So at 3:30 p.m. (Berlin time) on December 11, the German charge d’affaires in Washington handed American Secretary of State Cordell Hull a copy of the declaration of war. Italy declared war the same day.
The failure of the New Deal, argued Hitler at the Reichstag, was the real cause of the war, as President Roosevelt, supported by plutocrats and Jews, attempted to cover up for the collapse of his economic agenda. “First he incites war, then falsifies the causes, then odiously wraps himself in a cloak of Christian hypocrisy and slowly but surely leads mankind to war,” declared Hitler–and the Reichstag leaped to their feet in thunderous applause.
The U.S. Congress immediately declared war on them. President Roosevelt then made the defeat of Hitler the top priority, devoting nearly 90 percent of U.S. military resources to the war in Europe.